Transmission method, transmission device, and communication system

ABSTRACT

An indicator in a master AP from among a plurality of APs obtains communication quality of communication with an AP which is a communication partner. In the case where the obtained communication quality is less than a threshold, the indicator causes the plurality of APs including the master AP to perform cooperative operation to transmit data. In the case where the obtained communication quality is not less than the threshold, the indicator causes the plurality of APs including the master AP to stop the cooperative operation.

TECHNICAL FIELD

The present disclosure relates to a wireless communication technique.

BACKGROUND ART

Various frequency bandwidths are used in wireless communication. Inwireless LAN, for example, IEEE 802.11g uses a frequency bandwidth of2.4 GHz to 2.5 GHz band with a maximum transmission rate of 54 Mbps. Inmobile phones, for example, LTE uses a frequency bandwidth of 2 GHz witha maximum transmission rate of 112.5 Mbps.

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No.2013-258736

PTL 2: Japanese Unexamined Patent Application Publication (Translationof PCT Application) No. 2010-535450

PTL 3: Japanese Unexamined Patent Application Publication (Translationof PCT Application) No. 2014-534678

SUMMARY OF THE INVENTION

To achieve larger-capacity transmission, the introduction of wirelesscommunication using a frequency of 6 GHz or more, for example, afrequency bandwidth called millimeter wave, is desired.

In view of this, an aspect of the present disclosure provides, forexample, a transmission method used in a plurality of transmissiondevices that each perform wireless transmission to a reception deviceusing a millimeter wave frequency bandwidth, the transmission methodincluding: obtaining communication quality of communication with thereception device; causing the plurality of transmission devices toperform cooperative operation to transmit data, in the case where thecommunication quality obtained is less than a threshold; and stoppingthe cooperative operation, in the case where the communication qualityobtained is not less than the threshold.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or a recordingmedium, or any combination of systems, devices, methods, integratedcircuits, computer programs, or recording media.

With the transmission method according to the present disclosure,wireless transmission can be performed using a frequency bandwidth ofmillimeter wave in a plurality of transmission devices.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating the structure of wirelesscommunication system 100 according to Embodiment 1.

FIG. 2 is a block diagram illustrating the structure of AP 120.

FIG. 3 is a block diagram illustrating the structure of parent station110.

FIG. 4 is a diagram illustrating an example of transmitted data in thecase of setting all four APs 121, 122, 123, and 124 for multicast toperform transmission.

FIG. 5 is a diagram illustrating an example of transmitted data in thecase of setting APs 121 and 122 for multicast and APs 123 and 124 forunicast to perform transmission

FIG. 6 is a diagram illustrating an example of transmitted data in thecase of setting APs 121 and 122 for multicast and APs 123 and 124 forunicast to perform transmission

FIG. 7 is a diagram illustrating an example of received data in the caseof setting APs 121 and 122 for multicast and APs 123 and 124 for unicastto perform reception.

FIG. 8 is a diagram illustrating an example of received data in the caseof setting APs 121 and 122 for multicast and APs 123 and 124 for unicastto perform reception.

FIG. 9 is a diagram in which (A) illustrates an example of a mappingmethod in IQ plane of in-phase component I and quadrature component Qthat constitute a signal in QPSK modulation, and (B) illustrates anexample of a mapping method after phase change.

FIG. 10 is a diagram illustrating phase change by phase changer 1002.

FIG. 11 is a (first) sequence diagram illustrating packet transmissionoperation in parent station 110 and APs 121, 122, 123, and 124 inwireless communication system 100, followed by FIG. 12 .

FIG. 12 is a (second) sequence diagram illustrating packet transmissionoperation in parent station 110 and APs 121, 122, 123, and 124 inwireless communication system 100.

FIG. 13 is a sequence diagram illustrating packet reception operation inparent station 110 and APs 121, 122, 123, and 124 in wirelesscommunication system 100.

FIG. 14 is a block diagram illustrating the structure of wirelesscommunication system 1400 according to Variation (1).

FIG. 15 is a block diagram illustrating the structures of parent station1598 and APs 1599-1, 1599-2, 1599-3, and 1599-4 in wirelesscommunication system 1500 according to Variation (2).

FIG. 16 is a block diagram illustrating the structures of parent station1698 and APs 1699-1, 1699-2, 1699-3, and 1699-4 in wirelesscommunication system 1600 according to Variation (3).

FIG. 17 is a flowchart illustrating operation in the case where parentstation 110 newly places an AP under control in wireless communicationsystem 100.

FIG. 18 is a block diagram illustrating the structure of wirelesscommunication system 1800 according to Embodiment 2.

FIG. 19 is a block diagram illustrating the structure of AP 1820-1 whichis a master AP.

FIG. 20 is a block diagram illustrating the structure of AP 2000 whichis not a master AP.

FIG. 21 is a diagram illustrating an example of transmitted data in thecase of setting all APs 1820-1, 1820-2, 1820-3, and 1820-4 for multicastto perform transmission

FIG. 22 is a diagram illustrating an example of transmitted data in thecase of setting APs 1820-1 and 1820-2 for multicast and APs 1820-3 and1820-4 for unicast to perform transmission

FIG. 23 is a diagram illustrating an example of transmitted data in thecase of setting APs 1820-1 and 1820-2 for multicast and APs 1820-3 and1820-4 for unicast to perform transmission

FIG. 24 is a flowchart illustrating operation in the case where AP1820-1 which is a master AP newly places an AP under control in wirelesscommunication system 1800.

FIG. 25 is a block diagram illustrating the structure of wirelesscommunication system 2500 according to Embodiment 3.

FIG. 26 is a block diagram illustrating the structure of AP 2520.

FIG. 27 is a block diagram illustrating the structure of parent station2510.

FIG. 28 is a diagram illustrating an example of transmitted data in thecase of setting all APs 2520-1, 2520-2, 2520-3, and 2520-4 for multicastto perform transmission

FIG. 29 is a diagram illustrating another example of transmitted data inthe case of setting all APs 2520-1, 2520-2, 2520-3, and 2520-4 formulticast to perform transmission

FIG. 30 is a diagram illustrating an example of transmitted data in thecase of setting APs 2520-1 and 2520-2 for multicast and APs 2520-3 and2520-4 for unicast to perform transmission

FIG. 31 is a diagram illustrating another example of transmitted data inthe case of setting APs 2520-1 and 2520-2 for multicast and APs 2520-3and 2520-4 for unicast to perform transmission

FIG. 32 is a diagram illustrating an example of transmitted data in thecase of setting APs 2520-1 and 2520-2 for multicast and APs 2520-3 and2520-4 for unicast to perform transmission

FIG. 33 is a diagram illustrating another example of transmitted data inthe case of setting APs 2520-1 and 2520-2 for multicast and APs 2520-3and 2520-4 for unicast to perform transmission

FIG. 34 is a block diagram illustrating the structure of wirelesscommunication system 3400 according to Embodiment 4.

FIG. 35 is a block diagram illustrating the structure of AP 3420-1 whichis a master AP.

FIG. 36 is a block diagram illustrating the structure of AP 3600 whichis not a master AP.

FIG. 37 is a block diagram illustrating the structure of parent station3410.

FIG. 38 is a diagram illustrating an example of transmitted data in thecase of setting all APs 3420-1, 3420-2, 3420-3, and 3420-4 for multicastto perform transmission

FIG. 39 is a diagram illustrating another example of transmitted data inthe case of setting all APs 3420-1, 3420-2, 3420-3, and 3420-4 formulticast to perform transmission

FIG. 40 is a diagram illustrating an example of transmitted data in thecase of setting APs 3420-1 and 3420-2 for multicast and APs 3420-3 and3420-4 for unicast to perform transmission

FIG. 41 is a diagram illustrating another example of transmitted data inthe case of setting APs 3420-1 and 3420-2 for multicast and APs 3420-3and 3420-4 for unicast to perform transmission

FIG. 42 is a diagram illustrating an example of transmitted data in thecase of setting APs 3420-1 and 3420-2 for multicast and APs 3420-3 and3420-4 for unicast to perform transmission

FIG. 43 is a diagram illustrating another example of transmitted data inthe case of setting APs 3420-1 and 3420-2 for multicast and APs 3420-3and 3420-4 for unicast to perform transmission

FIG. 44 is a block diagram illustrating the structure of wirelesscommunication system 4400 according to Embodiment 5.

FIG. 45 is a block diagram illustrating the structure of AP 4420-1 whichis a master AP.

FIG. 46 is a block diagram illustrating the structure of AP 4600 whichis not a master AP.

FIG. 47 is a diagram illustrating an example of transmitted data in thecase of setting all APs 4420-1, 4420-2, 4420-3, and 4420-4 for unicastduring clear weather.

FIG. 48 is a diagram illustrating an example of transmitted data in thecase of setting all APs 4420-1, 4420-2, 4420-3, and 4420-4 for unicastduring rainfall.

FIG. 49 is a flowchart illustrating the operation of AP 4420-1 which isa master AP.

DESCRIPTION OF EXEMPLARY EMBODIMENTS 1. Underlying Knowledge FormingBasis of the Present Disclosure

As a method for realizing large-capacity transmission in a unit such asGbps, for example, a method of introducing a wireless communicationscheme that uses a frequency band such as millimeter wave is known.Radio waves in the millimeter wave frequency band have properties ofhigh straightness and fast attenuation. It is therefore difficult towiden the cell range within which radio waves reach.

The inventors of the present disclosure find it difficult to realize awireless communication system using radio waves in the millimeter wavefrequency band and having a wide cell range. The inventors of thepresent disclosure accordingly propose a new transmission scheme thatsolves this problem and achieves wireless communication using radiowaves in the millimeter wave frequency band.

The inventors of the present disclosure also acknowledge the demand torealize multicast or unicast communication using radio waves in themillimeter wave frequency band. In particular, there is a need for ascheme for accommodating many terminals in multicast. There is also aneed to realize unicast simultaneously with multicast.

Unicast refers to designating a single address in a network andtransmitting data to the specific destination. Multicast refers todesignating a plurality of destinations and transmitting data to thedestinations.

2. Embodiment 1

Wireless communication system 100 according to one embodiment of thepresent disclosure is described below.

2.1 Wireless Communication System 100

Wireless communication system 100 includes parent station 110, accesspoints (APs) 121, 122, 123, and 124, and terminals 131, 132, . . . ,138, as illustrated in FIG. 1 .

Parent station 110 is connected to a communication device (notillustrated) directly, or indirectly via a communication line. Thecommunication device is, for example, a broadcast device forbroadcasting data or a distribution system or a server for transmittingdata. The communication device transmits a control signal and data. Thecontrol signal includes unicast transmission method-related setting ormulticast transmission method-related setting, and phase change methodsetting (described later). The communication device may include aplurality of communication devices. In this case, a first communicationdevice may transmit the control signal, and a second communicationdevice may transmit the data. Parent station 110 is, for example,connected wiredly to APs 121, 122, 123, and 124. Parent station 110 maybe connected wirelessly to APs 121, 122, 123, and 124.

Parent station 110 receives the control signal and the data from thecommunication device. Parent station 110 transmits the control signaland the data to each of APs 121, 122, 123, and 124. APs 121, 122, 123,and 124 wirelessly transmit the data obtained from parent station 110.

Terminals 131, 132, . . . , 138 are each a mobile phone, a smartphone, atablet, or a personal computer (PC) that has a wireless communicationfunction using a frequency bandwidth of 6 GHz or more such as millimeterwave, e.g. a frequency bandwidth of 60 GHz.

Terminal 131, for example, wirelessly receives data from AP 121 in thecase where terminal 131 is located near AP 121. Terminals 132, 133, . .. , 138 each wirelessly receive data from its nearby AP, as withterminal 131.

Terminal 131 also wirelessly transmits data. In the case where terminal131 is located near AP 121, AP 121 wirelessly receives the data fromterminal 131. AP 121 transmits the received data to parent station 110.

Terminals 132, 133, . . . , 138 each wirelessly transmit data, as withterminal 131. An AP located near each terminal wirelessly receives thedata from the terminal. The AP transmits the data received from theterminal, to parent station 110.

Parent station 110 receives data from each terminal via a correspondingAP. Parent station 110 outputs the received data to the communicationdevice.

2.2 AP 120

APs 121, 122, 123, and 124, for example, have the same structure (samefunction). APs 121, 122, 123, and 124 are described below, as AP 120collectively.

AP 120 includes encoder 202, interleaver 204, mapping unit 206, phasechanger 208, wireless unit 210, antenna 212, antenna 215, and receptiondevice 217, as illustrated in FIG. 2 .

AP 120 receives control signal 214 from parent station 110. Controlsignal 214 includes unicast transmission method-related setting ormulticast transmission method-related setting, and phase change methodsetting.

AP 120 performs unicast transmission method-related setting, based oncontrol signal 214 received from parent station 110. AP 120 alsoperforms phase change method setting, based on control signal 214. Inthe case where multicast transmission is set, the AP is set to use thesame frequency (frequency band) as other APs.

In the case where unicast transmission is set, AP 120 operates receptiondevice 217. In the case where multicast transmission is set, AP 120 maystop the operation of reception device 217.

AP 120 performs wireless transmission/reception using the same channel(or the same frequency (frequency band)) in the case of unicasttransmission and in the case of multicast transmission. Here, AP 120 maydivide one wireless carrier into several time slots, and use each timeslot as a communication channel. Alternatively, AP 120 may use each of aplurality of different frequencies in the frequency bandwidth of 60 GHz,as a communication channel.

(1) Encoder 202

Encoder 202 receives data 201 from parent station 110. Encoder 202 alsoreceives control signal 213 from a controller included in AP 120.Control signal 213 includes information such as encoding schemedesignation, error correction scheme designation, encoding rate, andblock length. Encoder 202 performs error correction encoding, such asconvolution encoding, LDPC encoding, or turbo encoding, on data 201,using the schemes designated by control signal 213. Encoder 202 outputsencoded data 203.

(2) Interleaver 204

Interleaver 204 receives encoded data 203 from encoder 202. Interleaver204 also receives control signal 213 from the controller included in AP120. Control signal 213 includes interleave method designation.Interleaver 204 performs interleaving, i.e. rearrangement, on encodeddata 203, using the method designated by control signal 213. Interleaver204 outputs interleaved data 205.

(3) Mapping Unit 206

Mapping unit 206 receives interleaved data 205 from interleaver 204.Mapping unit 206 also receives control signal 213 from the controllerincluded in AP 120. Control signal 213 includes modulation schemedesignation. Mapping unit 206 performs modulation, such as quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),or 64 quadrature amplitude modulation (64QAM), on interleaved data 205according to the modulation scheme designation included in controlsignal 213, to generate modulated signal 207 (the modulation scheme isnot limited to such). Mapping unit 206 outputs modulated signal 207.

Mapping unit 206 may perform mapping including a phase change process.

(4) Phase Changer 208

Phase changer 208 receives modulated signal 207 from mapping unit 206.Phase changer 208 also receives control signal 214. Control signal 214includes phase change method setting. Phase changer 208 performs phasechange on modulated signal 207 according to the phase change methodsetting included in control signal 214, to generate phase-changed signal209. Phase changer 208 outputs phase-changed signal 209.

(5) Wireless Unit 210 and Antenna 212

Wireless unit 210 receives phase-changed signal 209 from phase changer208. Wireless unit 210 also receives control signal 213 from thecontroller included in AP 120. Control signal 213 includes designationof frequency conversion, amplification, etc. Wireless unit 210 performsprocesses such as frequency conversion and amplification onphase-changed signal 209, to generate transmission signal 211. Wirelessunit 210 outputs generated transmission signal 211 to antenna 212, usinga frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz.

Antenna 212 outputs transmission signal 211 as a radio wave.

(6) Antenna 215 and Reception Device 217

Antenna 215 receives signal 216 output from each terminal as a radiowave.

Reception device 217 receives signal 216 from antenna 215 using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz, and performs processes such asamplification and frequency conversion on signal 216, to generate data218. Reception device 217 outputs data 218 to parent station 110.

Although antennas 212 and 215 are described separately for convenience'ssake, they may be the same entity.

2.3 Parent Station 110

Parent station 110 includes transmission data separator 302, receptiondata separator 305, and indicator 308, as illustrated in FIG. 3 .

(1) Indicator 308

Indicator 308 is connected to the communication device and APs 121, 122,123, and 124.

For example, indicator 308 receives a control signal from thecommunication device. The control signal includes unicasttransmission-related setting or multicast transmission-related setting,and phase change method setting. For example, the communication deviceincludes a personal computer (PC) (or a computer, or the like), and theuser of the PC inputs the control signal through the PC.

A separate control signal may be set for each AP, or the same controlsignal may be set for all APs.

Multicast transmission may be set for all APs, or unicast transmissionmay be set for all APs. Multicast transmission may be set for part ofthe APs, and unicast transmission for the other APs. Thus, multicasttransmission-related setting and unicast-related setting may be mixedfor the APs.

For a plurality of APs set for multicast, the modulated signal beforephase change is the same signal. In other words, the same data istransmitted. A phase change method is then indicated to each AP.

For a plurality of APs set for unicast, the modulated signal beforephase change may be the same signal or a different signal. In otherwords, the same data may be transmitted, or different data may betransmitted.

Indicator 308 outputs the received control signal to transmission dataseparator 302, reception data separator 305, and APs 121, 122, 123, and124.

(2) Transmission Data Separator 302

Transmission data separator 302 is connected to the communicationdevice, indicator 308, and APs 121, 122, 123, and 124.

Transmission data separator 302 receives the control signal fromindicator 308. Transmission data separator 302 outputs the receivedcontrol signal to APs 121, 122, 123, and 124.

Transmission data separator 302 also receives data from thecommunication device. Transmission data separator 302 separates thereceived data into data for AP 121, data for AP 122, data for AP 123,and data for AP 124. Transmission data separator 302 outputs theseparated data to each of APs 121, 122, 123, and 124.

(3) Reception Data Separator 305

Reception data separator 305 is connected to the communication device,indicator 308, and APs 121, 122, 123, and 124.

Reception data separator 305 receives data from each of APs 121, 122,123, and 124. Reception data separator 305 outputs the received data tothe communication device.

2.4 Example of Transmitted/Received Data

An example of data transmitted/received by parent station 110 and APs121, 122, 123, and 124 is described below.

(1) In the Case of Setting all APs for Multicast Transmission toTransmit Data

An example of transmitted data in the case of setting all APs 121, 122,123, and 124 for multicast transmission to transmit data is describedbelow, with reference to FIG. 4 .

Transmission data separator 302 receives packets 401, 402, 403, 404, . .. in this order, as illustrated in FIG. 4 . Packets 401, 402, 403, 404,. . . are all multicast packets. Packets 401, 402, 403, 404, . . . aregenerated from one set of multicast data.

In the case where all APs are set for multicast, transmission dataseparator 302, upon receiving packet 401, outputs same packet 401 to APs121, 122, 123, and 124. APs 121, 122, 123, and 124 wirelessly outputpackets 406, 411, 416, and 421 respectively. Packets 406, 411, 416, and421 are generated based on and correspond to same packet 401.

Next, upon receiving packet 402, transmission data separator 302 outputssame packet 402 to APs 121, 122, 123, and 124. APs 121, 122, 123, and124 wirelessly output packets 407, 412, 417, and 422 respectively, inmulticast. Packets 407, 412, 417, and 422 are generated based on andcorrespond to same packet 402.

Next, upon receiving packet 403, transmission data separator 302 outputssame packet 403 to APs 121, 122, 123, and 124. APs 121, 122, 123, and124 wirelessly output packets 408, 413, 418, and 423 respectively, inmulticast. Packets 408, 413, 418, and 423 are generated based on andcorrespond to same packet 403.

Next, upon receiving packet 404, transmission data separator 302 outputssame packet 404 to APs 121, 122, 123, and 124. APs 121, 122, 123, and124 wirelessly output packets 409, 414, 419, and 424 respectively, inmulticast. Packets 409, 414, 419, and 424 are generated based on andcorrespond to same packet 404.

In this case, a feature lies in that APs 121, 122, 123, and 124 eachperform phase change on the modulated signal (alternatively, any of APs121, 122, 123, and 124 may perform no phase change).

(The phase change method will be described in detail later.)

This has the advantages of widening the cell range within the reach of amulticast modulated signal, and reducing, by means of phase change,points at which reception is difficult due to modulated signalinterference.

(2) In the Case of Setting Two APs for Multicast Transmission toTransmit Data

An example of transmitted data in the case of setting two APs 121 and122 as multicast data transmission APs and other two APs 123 and 124 asunicast data transmission APs to transmit data is described below, withreference to FIG. 5 . In this case, APs 121 and 122 transmit the samedata (the modulated signal after mapping and before phase change is thesame). Moreover, APs 123 and 124 transmit the same data (the modulatedsignal after mapping and before phase change is the same).

Transmission data separator 302 receives packets 501, 502, 503, 504,505, 506, . . . in this order, as illustrated in FIG. 5 . Packets 501,503, 504, 506, . . . are multicast packets. Packets 502 and 505 areunicast packets.

Packets 501, 503, 504, and 506 are generated from one set of multicastdata. Packets 502 and 505 are generated from one set of unicast data.

Upon receiving packet 501, transmission data separator 302 outputs samepacket 501 to APs 121 and 122. APs 121 and 122 wirelessly output packets511 and 521 respectively, in multicast transmission. Packets 511 and 521are generated based on and correspond to same packet 501.

Next, upon receiving packet 502, transmission data separator 302 outputssame packet 502 to APs 123 and 124. APs 123 and 124 wirelessly outputpackets 531 and 541 respectively, in unicast transmission. Packets 531and 541 are generated based on and correspond to same packet 502.

Next, upon receiving packet 503, transmission data separator 302 outputssame packet 503 to APs 121 and 122. APs 121 and 122 wirelessly outputpackets 512 and 522 respectively, in multicast transmission. Packets 512and 522 are generated based on and correspond to same packet 503.

Next, upon receiving packet 504, transmission data separator 302 outputssame packet 504 to APs 121 and 122. APs 121 and 122 wirelessly outputpackets 513 and 523 respectively, in multicast transmission. Packets 513and 523 are generated based on and correspond to same packet 504.

Next, upon receiving packet 505, transmission data separator 302 outputssame packet 505 to APs 123 and 124. APs 123 and 124 wirelessly outputpackets 532 and 542 respectively, in unicast transmission. Packets 532and 542 are generated based on and correspond to same packet 505.

Next, upon receiving packet 506, transmission data separator 302 outputssame packet 506 to APs 121 and 122. APs 121 and 122 wirelessly outputpackets 514 and 524 respectively, in multicast transmission. Packets 514and 524 are generated based on and correspond to same packet 506.

As described above, in the case of transmitting the modulated signal inunicast transmission, the packets transmitted in APs 123 and 124 arebased on the same data. Here, APs 123 and 124 have the same transmissionparameter. APs 123 and 124 may perform different phase changes.Alternatively, any of APs 123 and 124 may perform no phase change.

This has the advantages of widening the cell range within the reach of aunicast modulated signal, and reducing, by means of phase change, pointsat which reception is difficult due to modulated signal interference.

A feature lies in that APs 121 and 122 each perform phase change on themodulated signal. Alternatively, any of APs 121 and 122 may perform nophase change. The phase change method will be described in detail later.

This has the advantages of widening the cell range within the reach of amulticast modulated signal, and reducing, by means of phase change,points at which reception is difficult due to modulated signalinterference.

(3) In the Case of Setting Two APs for Multicast Transmission toTransmit Data

An example of transmitted data in the case of setting two APs 121 and122 for multicast transmission to transmit data and setting other twoAPs 123 and 124 for unicast transmission to transmit data is describedbelow, with reference to FIG. 6 . In FIG. 6 , APs 123 and 124 transmitdifferent data, unlike in FIG. 5 .

Transmission data separator 302 receives packets 601, 602, 603, 604,605, 606, 607, 608, 609, 610, . . . in this order, as illustrated inFIG. 6 . Packets 601, 603, 604, and 606 are multicast packets. Packets602, 607, and 609 are unicast packets transmitted by AP 123. Packets605, 608, and 610 are unicast packets transmitted by AP 124.

Packets 601, 603, 604, and 606 are generated from one set of multicastdata. Packets 602, 607, and 609 are generated from one set of unicastdata. Packets 605, 608, and 610 are generated from another set ofunicast data.

Upon receiving packet 601, transmission data separator 302 outputs samepacket 601 to APs 121 and 122. APs 121 and 122 wirelessly output packets621 and 625 respectively, in multicast transmission. Packets 621 and 625are generated based on and correspond to same packet 601.

Next, upon receiving packet 602, transmission data separator 302 outputspacket 602 to AP 123. AP 123 wirelessly outputs packet 631, in unicasttransmission.

Next, upon receiving packet 603, transmission data separator 302 outputssame packet 603 to APs 121 and 122. APs 121 and 122 wirelessly outputpackets 622 and 626 respectively, in multicast transmission. Packets 622and 626 are generated based on and correspond to same packet 603.

Next, upon receiving packet 604, transmission data separator 302 outputssame packet 604 to APs 121 and 122. APs 121 and 122 wirelessly outputpackets 623 and 627 respectively, in multicast transmission. Packets 623and 627 are generated based on and correspond to same packet 604.

Next, upon receiving packet 605, transmission data separator 302 outputspacket 605 to AP 124. AP 124 wirelessly outputs packet 641, in unicasttransmission.

Next, upon receiving packet 606, transmission data separator 302 outputssame packet 606 to APs 121 and 122. APs 121 and 122 wirelessly outputpackets 624 and 628 respectively, in multicast transmission. Packets 624and 628 are generated based on and correspond to same packet 606.

Next, upon receiving packet 607, transmission data separator 302 outputspacket 607 to AP 123. AP 123 wirelessly outputs packet 632, in unicasttransmission.

Next, upon receiving packet 608, transmission data separator 302 outputspacket 608 to AP 124. AP 124 wirelessly outputs packet 642, in unicasttransmission.

Next, upon receiving packet 609, transmission data separator 302 outputspacket 609 to AP 123. AP 123 wirelessly outputs packet 633, in unicasttransmission.

Next, upon receiving packet 610, transmission data separator 302 outputspacket 610 to AP 124. AP 124 wirelessly outputs packet 643, in unicasttransmission.

A feature lies in that APs 121 and 122 each perform phase change on themodulated signal. Alternatively, any of APs 121 and 122 may perform nophase change. The phase change method will be described in detail later.

This has the advantages of widening the cell range within the reach of amulticast modulated signal, and reducing, by means of phase change,points at which reception is difficult due to modulated signalinterference.

Moreover, a flexible system in which APs 123 and 124 can perform unicastcommunication is realized.

There is thus the advantage of realizing a flexible system by, forexample, switching the transmission state among the transmission statein FIG. 4 , the transmission state in FIG. 5 , and the transmissionstate in FIG. 6 depending on time (e.g. switching depending on theterminal presence situation).

(4) In the Case of Setting Two APs for Multicast Transmission to ReceiveData

An example of received data in the case of setting two APs 121 and 122for multicast transmission and other two APs 123 and 124 for unicasttransmission to receive data is described below, with reference to FIG.7 . In this case, APs 121 and 122 do not receive data (because they aremulticast transmission APs). Meanwhile, APs 123 and 124 receive signalsincluding the same data.

Reception device 217 in AP 123 receives and obtains packets 711, 712,713, . . . in this order. Reception device 217 in AP 124 receives andobtains packets 721, 722, 723, . . . in this order. Suppose one packetbetween packets 712 and 713 received by reception device 217 in AP 123is not obtained. Also suppose one packet between packets 721 and 722received by reception device 217 in AP 124 is not obtained.

When reception device 217 in AP 123 receives packet 711, reception dataseparator 305 receives packet 701. Packets 711 and 702 correspond toeach other.

Next, when reception device 217 in AP 124 receives packet 721, receptiondata separator 305 receives packet 702. Packets 721 and 702 correspondto each other.

Next, when reception device 217 in AP 123 receives packet 712, receptiondata separator 305 receives packet 703. Packets 712 and 703 correspondto each other.

Next, when reception device 217 in AP 124 receives packet 722, receptiondata separator 305 receives packet 704. Packets 722 and 704 correspondto each other.

Next, when reception device 217 in AP 123 receives packet 713, receptiondata separator 305 receives packet 705. Packets 713 and 705 correspondto each other.

Next, when reception device 217 in AP 124 receives packet 723, receptiondata separator 305 receives packet 706. Packets 723 and 706 correspondto each other.

For example, APs 123 and 124 may perform maximum ratio combining, andthen perform demodulation/decoding, to obtain packets.

(5) In the Case of Setting Two APs for Multicast Transmission to ReceiveData

An example of received data in the case of setting two APs 121 and 122for multicast transmission and other two APs 123 and 124 for unicasttransmission to receive data is described below, with reference to FIG.8 . In this case, APs 121 and 122 do not receive data. Meanwhile, APs123 and 124 receive different data.

Reception device 217 in AP 123 receives packets 811, 812, 813, 814, . .. in this order, in unicast. Reception device 217 in AP 124 receivespackets 816, 817, 818, 819, . . . in this order, in unicast.

Packets 811, 812, 813, 814, . . . are generated from one set of unicastdata. Packets 816, 817, 818, 819, . . . are generated from another setof unicast data.

When reception device 217 in AP 123 receives packet 811, reception dataseparator 305 receives packet 801. Packets 811 and 801 correspond toeach other.

When reception device 217 in AP 124 receives packet 816, reception dataseparator 305 receives packet 802. Packets 816 and 802 correspond toeach other.

When reception device 217 in AP 123 receives packet 812, reception dataseparator 305 receives packet 803. Packets 812 and 803 correspond toeach other.

When reception device 217 in AP 123 receives packet 813, reception dataseparator 305 receives packet 804. Packets 813 and 804 correspond toeach other.

When reception device 217 in AP 124 receives packet 817, reception dataseparator 305 receives packet 805. Packets 817 and 805 correspond toeach other.

2.5 Mapping Method and Phase Change

(A) in FIG. 9 illustrates an example of a mapping method in IQ plane ofin-phase component I and quadrature component Q that constitute a signalin QPSK modulation.

As illustrated in (A) in FIG. 9 , for example in the case where inputdata is “00”, mapping unit 206 outputs in-phase component I=r andquadrature component Q=r of a baseband signal. Likewise, in the casewhere input data is “01”, mapping unit 206 outputs in-phase componentI=−r and quadrature component Q=r of a baseband signal. In the casewhere input data is “10”, mapping unit 206 outputs in-phase componentI=r and quadrature component Q=−r of a baseband signal. Likewise, in thecase where input data is “11”, mapping unit 206 outputs in-phasecomponent I=−r and quadrature component Q=−r of a baseband signal.Signal points 901, 902, 903, and 904 illustrated in (A) in FIG. 9 arethus obtained. (B) in FIG. 9 illustrates an example of a mapping methodafter phase change.

Rotating signal points 901, 902, 903, and 904 in (A) in FIG. 9 by θ(u)about the origin point (where u is a symbol number) yields signal points911, 912, 913, and 914 in (B) in FIG. 9 . The phase change value is afunction of symbol number u, and so is denoted as θ(u).

2.6 Phase Changer

AP 120 in wireless communication system 100 may include phase changer1002 illustrated in FIG. 10 , instead of phase changer 208 illustratedin FIG. 2 .

Phase changer 1002 receives modulated baseband signal s(t)(1001).

Phase changer 1002 calculates phase-changed signal z(t), according tothe following Expression (1).

[Math. 1]

z(t)=y(t)×s(t) (where t is time)  Expression (1).

Phase changer 1002 outputs phase-changed signal z(t)(1005).

Here, y(t) may be set as follows.

$\begin{matrix}{\begin{matrix}{{y(u)} = e^{j0}} & \left( {{{at}{time}}u} \right) \\{{y\left( {u + 1} \right)} = e^{j\frac{\pi}{2}}} & \left( {{{at}{time}u} + 1} \right) \\{{y\left( {u + 2} \right)} = e^{j\pi}} & \left( {{{at}{time}u} + 2} \right) \\{{y\left( {u + 3} \right)} = \text{?}} & \left( {{{at}{time}u} + 3} \right) \\ \vdots & \\{{y\left( {u + k} \right)} = e^{j\frac{k\pi}{2}}} & \left( {{{at}{time}u} + k} \right) \\ \vdots & \end{matrix}} & \left\lbrack {{Math}.2} \right\rbrack\end{matrix}$ ?indicates text missing or illegible when filed

Phase changer 1002 may calculate phase-changed signal z(f) according toExpression (3), instead of z(t).

[Math. 3]

z(f)=y(f)×s(f) (where f is frequency)  Expression (3).

In this case, phase changer 1002 outputs phase-changed signal z(f).

Wireless communication system 100 may hold a plurality of phase changepatterns. Each AP is then assigned one phase change pattern.

For example, wireless communication system 100 holds four phase changepatterns of cycles N1, N2, N3, and N4. A phase change pattern of cycleN1 (the phase change value is denoted as y1(i), where y1(i) is afunction of symbol number i) is assigned to AP 121. A phase changepattern of cycle N2 (the phase change value is denoted as y2(i), wherey2(i) is a function of symbol number i) is assigned to AP 122. A phasechange pattern of cycle N3 (the phase change value is denoted as y3(i),where y3(i) is a function of symbol number i) is assigned to AP 123. Aphase change pattern of cycle N4 (the phase change value is denoted asy4(i), where y4(i) is a function of symbol number i) is assigned to AP124.

Phase changer 1002 in AP 121 calculates phase-changed signal z(i)according to the following Expression (4).

[Math. 4]

z(i)=1(k)×s(i)  Expression (4).

Here, k=i mod N1, where N1 is an integer greater than or equal to 2, andi is, for example, an integer greater than or equal to 0. i mod N1denotes the remainder after division of i by N1 (mod: modulo).

Phase changer 1002 in AP 122 calculates phase-changed signal z(i),according to the following Expression (5).

[Math. 5]

z(i)=y2(k)×s(i)  Expression (5).

Here, k=i mod N2, where N2 is an integer greater than or equal to 2, andi is, for example, an integer greater than or equal to 0. i mod N2denotes the remainder after division of i by N2 (mod: modulo).

Phase changer 1002 in AP 123 calculates phase-changed signal z(i),according to the following Expression (6).

[Math. 6]

z(i)=y3(k)×s(i)  Expression (6).

Here, k=i mod N3, where N3 is an integer greater than or equal to 2, andi is, for example, an integer greater than or equal to 0. i mod N3denotes the remainder after division of i by N3 (mod: modulo).

Phase changer 1002 in AP 124 calculates phase-changed signal z(i),according to the following Expression (7).

[Math. 7]

z(i)=y4(k)×s(i)  Expression (7).

Here, k=i mod N4, where N4 is an integer greater than or equal to 2, andi is, for example, an integer greater than or equal to 0. i mod N4denotes the remainder after division of i by N4 (mod: modulo).

If possible, different phase change patterns are preferably used. In thecase where a first AP and a second AP are near each other, the phasechange pattern assigned to the first AP and the phase change patternassigned to the second AP may be different.

Alternatively, the phase change pattern assigned to the first AP and thephase change pattern assigned to the second AP may be the same.

Any of APs 121, 122, 123, and 124 may perform no phase change.

2.7 Operation in Wireless Communication System 100

Operation in wireless communication system 100 is described below.

(1) Packet Transmission Operation

Packet transmission operation in parent station 110 and APs 121, 122,123, and 124 in wireless communication system 100 is described below,with reference to sequence diagrams in FIGS. 11 to 12 .

The communication device generates a packet (Step S1101), and transmitsthe generated packet to parent station 110 (Step S1102). Thecommunication device returns to Step S1101, and repeats packetgeneration and packet transmission.

Transmission data separator 302 receives the packet from thecommunication device (Step S1102). Transmission data separator 302determines whether the received packet is for multicast or for unicast(Step S1103). In the case where the received packet is for unicast (StepS1103: “unicast”), transmission data separator 302 transfers control toStep S1216.

In the case where the received packet is for multicast (Step S1103:“multicast”), transmission data separator 302 determines whether or notAP 121 is set for multicast (Step S1104). In the case where AP 121 isset for multicast (Step S1104: “multicast”), transmission data separator302 outputs the received packet to AP 121 (Step S1105). AP 121 receivesthe packet (Step S1105). AP 121 performs processes such as encoding,interleaving, mapping, and phase change (Step S1106). AP 121 thenwirelessly outputs a signal (Step S1107).

In the case where AP 121 is not set for multicast (Step S1104: “No”),transmission data separator 302 determines whether or not AP 122 is setfor multicast (Step S1108). In the case where AP 122 is set formulticast (Step S1108: “multicast”), transmission data separator 302outputs the received packet to AP 122 (Step S1109). AP 122 receives thepacket (Step S1109). AP 122 performs processes such as encoding,interleaving, mapping, and phase change (Step S1110). AP 122 thenwirelessly outputs a signal (Step S1111).

In the case where AP 122 is not set for multicast (Step S1108: “No”),transmission data separator 302 determines whether or not AP 123 is setfor multicast (Step S1112). In the case where AP 123 is set formulticast (Step S1112: “multicast”), transmission data separator 302outputs the received packet to AP 123 (Step S1113). AP 123 receives thepacket (Step S1113). AP 123 performs processes such as encoding,interleaving, mapping, and phase change, and wirelessly outputs asignal.

In the case where AP 123 is not set for multicast (Step S1112: “No”),transmission data separator 302 determines whether or not AP 124 is setfor multicast (Step S1114). In the case where AP 124 is set formulticast (Step S1114: “multicast”), transmission data separator 302outputs the received packet to AP 124 (Step S1115). AP 124 receives thepacket (Step S1115). AP 124 performs processes such as encoding,interleaving, mapping, and phase change, and wirelessly outputs asignal.

In the case where AP 124 is not set for multicast (Step S1114: “No”),transmission data separator 302 returns control to Step S1102.

In the case where the received packet is for unicast (Step S1103:“unicast”), transmission data separator 302 determines whether or not AP121 is set for unicast (Step S1216). In the case where AP 121 is set forunicast (Step S1216: “unicast”), transmission data separator 302 outputsthe received packet to AP 121 (Step S1217). AP 121 receives the packet(Step S1217). AP 121 performs processes such as encoding, interleaving,mapping, and phase change (Step S1218). AP 121 then wirelessly outputs asignal (Step S1219).

In the case where AP 121 is not set for unicast (Step S1216: “No”),transmission data separator 302 determines whether or not AP 122 is setfor unicast (Step S1220). In the case where AP 122 is set for unicast(Step S1220: “unicast”), transmission data separator 302 outputs thereceived packet to AP 122 (Step S1221). AP 122 receives the packet (StepS1221). AP 122 performs processes such as encoding, interleaving,mapping, and phase change (Step S1222). AP 122 then wirelessly outputs asignal (Step S1223).

In the case where AP 122 is not set for unicast (Step S1220: “No”),transmission data separator 302 determines whether or not AP 123 is setfor unicast (Step S1224). In the case where AP 123 is set for unicast(Step S1224: “unicast”), transmission data separator 302 outputs thereceived packet to AP 123 (Step S1225). AP 123 receives the packet (StepS1225). AP 123 performs processes such as encoding, interleaving,mapping, and phase change, and wirelessly outputs a signal.

In the case where AP 123 is not set for unicast (Step S1224: “No”),transmission data separator 302 determines whether or not AP 124 is setfor unicast (Step S1226). In the case where AP 124 is set for unicast(Step S1226: “unicast”), transmission data separator 302 outputs thereceived packet to AP 124 (Step S1227). AP 124 receives the packet (StepS1227). AP 124 performs processes such as encoding, interleaving,mapping, and phase change, and wirelessly outputs a signal.

In the case where AP 124 is not set for unicast (Step S1226: “No”),transmission data separator 302 returns control to Step S1102.

(2) Packet Reception Operation

Packet reception operation in parent station 110 and APs 121, 122, 123,and 124 in wireless communication system 100 is described below, withreference to a sequence diagram in FIG. 13 .

Reception device 217 in AP 121 wirelessly receives a signal (StepS1351). Reception device 217 then outputs a packet to parent station 110(Step S1352). Reception device 217 returns control to Step S1351 (StepS1353), and repeats wireless reception and packet output.

Reception data separator 305 receives the packet from reception device217 in AP 121 (Step S1352). Reception data separator 305 outputs thereceived packet to the communication device (Step S1354).

Reception device 217 in AP 122 wirelessly receives a signal (StepS1356). Reception device 217 then outputs a packet to parent station 110(Step S1357). Reception device 217 returns control to Step S1356 (StepS1358), and repeats wireless reception and packet output.

Reception data separator 305 receives the packet from reception device217 in AP 122 (Step S1357). Reception data separator 305 outputs thereceived packet to the communication device (Step S1359).

Reception device 217 in AP 123 wirelessly receives a signal (StepS1361). Reception device 217 then outputs a packet to parent station 110(Step S1362). Reception device 217 returns control to Step S1361 (StepS1363), and repeats wireless reception and packet output.

Reception data separator 305 receives the packet from reception device217 in AP 123 (Step S1362). Reception data separator 305 outputs thereceived packet to the communication device (Step S1364).

Reception device 217 in AP 124 wirelessly receives a signal (StepS1366). Reception device 217 then outputs a packet to parent station 110(Step S1367). Reception device 217 returns control to Step S1366 (StepS1368), and repeats wireless reception and packet output.

Reception data separator 305 receives the packet from reception device217 in AP 124 (Step S1367). Reception data separator 305 outputs thereceived packet to the communication device (Step S1369).

2.8 Variation (1)

Wireless communication system 1400 as a variation of wirelesscommunication system 100 is described below.

In wireless communication system 100, parent station 110 is wiredlyconnected to each of APs 121, 122, 123, and 124 (or may be wirelesslyconnected to each of APs 121, 122, 123, and 124). In other words, parentstation 110 and APs 121, 122, 123, and 124 are wiredly (or wirelessly)connected in parallel. However, this is not a limitation.

Wireless communication system 1400 has a structure similar to that ofwireless communication system 100. The differences from wirelesscommunication system 100 are mainly described below.

Wireless communication system 1400 includes parent station 1410, APs1421, 1422, 1423, and 1424, and terminals 1431, 1432, . . . , 1438, asillustrated in FIG. 14 .

In wireless communication system 1400, parent station 1410 is wiredly(or wirelessly) connected to AP 1421. AP 1421 is wiredly (or wirelessly)connected to AP 1422, AP 1422 is wiredly (or wirelessly) connected to AP1423, and AP 1423 is wiredly (or wirelessly) connected to AP 1424. Inother words, parent station 1410 and APs 1421, 1422, 1423, and 1424 arewiredly (or wirelessly) connected in series.

(Packet Transmission in Direction from Parent Station 1410 to Terminal)

Parent station 1410 transmits a packet for AP 1421, a packet for AP1422, a packet for AP 1423, and a packet for AP 1424, to AP 1421.

AP 1421 receives the packet for AP 1421, the packet for AP 1422, thepacket for AP 1423, and the packet for AP 1424, from parent station1410.

Upon receiving the packet for AP 1421, AP 1421 performs processes suchas encoding on the packet, and wirelessly outputs it.

Upon obtaining the packet for AP 1422, the packet for AP 1423, and thepacket for AP 1424, AP 1421 transmits the packet for AP 1422, the packetfor AP 1423, and the packet for AP 1424, to AP 1422.

AP 1422 receives the packet for AP 1422, the packet for AP 1423, and thepacket for AP 1424, from AP 1421.

Upon receiving the packet for AP 1422, AP 1422 performs processes suchas encoding on the packet, and wirelessly outputs it.

Upon obtaining the packet for AP 1423 and the packet for AP 1424, AP1422 transmits the received packet for AP 1423 and packet for AP 1424,to AP 1423.

AP 1423 receives the packet for AP 1423 and the packet for AP 1424, fromAP 1422.

Upon receiving the packet for AP 1423, AP 1423 performs processes suchas encoding on the packet, and wirelessly outputs it.

Upon obtaining the packet for AP 1424, AP 1423 transmits the receivedpacket for AP 1424, to AP 1424.

AP 1424 receives the packet for AP 1424, from AP 1423.

Upon receiving the packet for AP 1424, AP 1424 performs processes suchas encoding on the packet, and wirelessly outputs it.

(Packet Transmission in Direction from Terminal to Parent Station 1410)

Terminals 1431, 1432, . . . , 1438 each wirelessly transmit a packet.

AP 1424 receives a packet transmitted from any of the terminals. Uponreceiving the packet, AP 1424 transmits the received packet to AP 1423.

AP 1423 receives a packet transmitted from any of the terminals. AP 1423also receives the packet (the packet wirelessly received by AP 1424 froma terminal), from AP 1424. Upon receiving the packet from the terminaland the packet from AP 1424, AP 1423 transmits the packet from theterminal and the packet from AP 1424, to AP 1422.

AP 1422 receives a packet transmitted from any of the terminals. AP 1422also receives the packets (the packet wirelessly received by AP 1424from a terminal and the packet wirelessly received by AP 1423 from aterminal), from AP 1423. Upon receiving the packet from the terminal andthe packets from AP 1423, AP 1422 transmits the packet from the terminaland the packets from AP 1423, to AP 1421.

AP 1421 receives a packet transmitted from any of the terminals. AP 1421also receives the packets (the packet wirelessly received by AP 1424from a terminal, the packet wirelessly received by AP 1423 from aterminal, and the packet wirelessly received by AP 1422 from aterminal), from AP 1422. Upon receiving the packet from the terminal andthe packets from AP 1422, AP 1421 transmits the packet from the terminaland the packets from AP 1422, to parent station 1410.

2.9 Variation (2)

Wireless communication system 1500 as a variation of wirelesscommunication system 100 is described below.

Wireless communication system 1500 has a structure similar to that ofwireless communication system 100. Wireless communication system 1500includes parent station 1598 and APs 1599-1, 1599-2, 1599-3, and 1599-4instead of parent station 110 and APs 121, 122, 123, and 124 in wirelesscommunication system 100, as illustrated in FIG. 15 . The differencesfrom wireless communication system 100 are mainly described below.

Parent station 1598 and APs 1599-1, 1599-2, 1599-3, and 1599-4respectively correspond to parent station 110 and APs 121, 122, 123, and124 in wireless communication system 100.

Parent station 1598 includes indicator 1504, transmission data separator1502, AP #1 transmission signal processor 1507-1, AP #2 transmissionsignal processor 1507-2, AP #3 transmission signal processor 1507-3, AP#4 transmission signal processor 1507-4 and reception data separator 305(not illustrated).

AP 1599-1 includes AP #1 transmission processor 1509-1 and antenna1511-1. AP 1599-2 includes AP #2 transmission processor 1509-2 andantenna 1511-2. AP 1599-3 includes AP #3 transmission processor 1509-3and antenna 1511-3. AP 1599-4 includes AP #4 transmission processor1509-4 and antenna 1511-4.

APs 1599-1, 1599-2, 1599-3, and 1599-4 do not perform at least theprocesses of error correction encoding, interleaving, mapping, and phasechange.

AP #1 transmission signal processor 1507-1, AP #2 transmission signalprocessor 1507-2, AP #3 transmission signal processor 1507-3, and AP #4transmission signal processor 1507-4 perform the processes of errorcorrection encoding, interleaving, mapping, and phase change,respectively for APs 1599-1, 1599-2, 1599-3, and 1599-4.

In particular, a feature lies in that AP #1 transmission signalprocessor 1507-1, AP #2 transmission signal processor 1507-2, AP #3transmission signal processor 1507-3, and AP #4 transmission signalprocessor 1507-4 each perform the phase change process.

AP #1 transmission processor 1509-1, AP #2 transmission processor1509-2, AP #3 transmission processor 1509-3, and AP #4 transmissionprocessor 1509-4 each perform processes such as frequency conversion andpower amplification.

The processes by indicator 1504 and the processes by transmission dataseparator 1502 are respectively the same as the processes by indicator308 and the processes by transmission data separator 302 in wirelesscommunication system 100.

An example of the processes by transmission data separator 1502 is asdescribed with reference to FIGS. 4 to 6 .

2.10 Variation (3)

Wireless communication system 1600 as a variation of wirelesscommunication system 100 is described below.

Wireless communication system 1600 has a structure similar to that ofwireless communication system 100. Wireless communication system 1600includes parent station 1698 and APs 1699-1, 1699-2, 1699-3, and 1699-4instead of parent station 110 and APs 121, 122, 123, and 124 in wirelesscommunication system 100, as illustrated in FIG. 16 . The differencesfrom wireless communication system 100 are mainly described below.

The major difference from wireless communication system 100 is that thefunction of the reception process (demodulation, decoding) is sharedbetween parent station 1698 and APs 1699-1, 1699-2, 1699-3, and 1699-4.

Parent station 1698 and APs 1699-1, 1699-2, 1699-3, and 1699-4respectively correspond to parent station 110 and APs 121, 122, 123, and124 in wireless communication system 100.

Parent station 1698 includes indicator 1610, reception data separator1607, AP #1 reception signal processor 1605-1, AP #2 reception signalprocessor 1605-2, AP #3 reception signal processor 1605-3, AP #4reception signal processor 1605-4, and transmission data separator 302(not illustrated).

AP 1699-1 includes AP #1 reception processor 1603-1 and antenna 1601-1.AP 1699-2 includes AP #2 reception processor 1603-2 and antenna 1601-2.AP 1699-3 includes AP #3 reception processor 1603-3 and antenna 1601-3.AP 1699-4 includes AP #4 reception processor 1603-4 and antenna 1601-4.

AP #1 reception processor 1603-1, AP #2 reception processor 1603-2, AP#3 reception processor 1603-3, and AP #4 reception processor 1603-4 eachperform processes such as frequency conversion.

The processes by indicator 1610 and the processes by reception dataseparator 1607 are respectively the same as the processes by indicator308 and the processes by reception data separator 305 in wirelesscommunication system 100.

An example of the processes by reception data separator 1607 is asdescribed with reference to FIGS. 7 and 8 .

1.11 Operation in the Case where Parent Station Places AP Under Control

Operation in the case where parent station 110 newly places an AP undercontrol in wireless communication system 100 is described below, withreference to a flowchart in FIG. 17 .

Suppose four APs 121, 122, 123, and 124 are under control of parentstation 110, and then a new AP is to be added. At this point, the phasechange patterns (and IDs) have already been set for four APs 121, 122,123, and 124.

An AP that intends to be newly placed under control of parent station110 notifies parent station 110 of a request to be placed under controlof parent station 110. Parent station 110 receives the request from thenew AP (Step S1701).

Parent station 110 determines whether or not to place the new AP underits control (Step S1702). In the case of determining to place the new APunder its control (Step S1702: “Yes”), parent station 110 assigns an IDto the new AP. Here, the ID is associated with a phase change pattern.The new AP sets the phase change pattern from the assigned ID (StepS1703). This completes the operation in the case of newly placing an APunder control.

In the case of determining not to place the new AP under its control(Step S1702: “No”), parent station 110 notifies the new AP that the APis not to be placed under its control (Step S1704). This completes theoperation in the case of newly placing an AP under control.

Step S1703 may be performed as follows.

Parent station 110 transmits information indicating the phase changepattern to be set by the new AP, to the new AP. The new AP receives theinformation indicating the phase change pattern, and sets the phasechange pattern in the AP based on the received information indicatingthe phase change pattern. Here, parent station 110 may or may not assignthe ID to the new AP. Assigning the ID here has the advantage that, inthe case where parent station 110 designates the AP newly placed underits control as a unicast AP or a multicast AP, the ID and unicast ormulticast can be easily designated for the AP by transmittinginformation “ID and unicast or multicast” to the AP.

The above describes the case where four APs 121, 122, 123, and 124 areunder control of parent station 110 and then a new AP is to be added.However, this is not a limitation.

There may be no AP under control of parent station 110 in an initialstate. In such a case, APs may be placed under control of parent station110 one by one, as described above.

In Step S1702, parent station 110 may determine whether or not to placethe new AP under its control, depending on a limit to the number of APsplaced under its control. Parent station 110 stores a maximum value ofthe number of APs placed under its control. When there is a request fromone AP to be newly placed under its control, parent station 110 adds “1”to the number of APs currently under its control, and compares theobtained value with the maximum value. In the case where the obtainedvalue is not greater than the maximum value, parent station 110 permitsthe AP to be under its control. In the case where the obtained value isgreater than the maximum value, parent station 110 does not permit theAP to be under its control.

In Step S1702, parent station 110 may determine whether or not to placethe new AP under its control, depending on the position of the new APand the phase change pattern.

For example, when the new AP is away from each AP already under itscontrol, parent station 110 permits the new AP to be under its control.

For example, when the new AP is near any AP already under its control,if there is a phase change pattern to be assigned to the new AP, parentstation 110 permits the new AP to be under its control.

For example, when the new AP is near any AP already under its control,if there is no phase change pattern to be assigned to the new AP, parentstation 110 does not permit the new AP to be under its control.

2.11 Conclusion

According to this embodiment, large-capacity transmission of Gbps levelcan be achieved. Moreover, the number of terminals accommodated in thecase of implementing multicast can be increased. Furthermore, unicastcommunication can be realized simultaneously with multicast. A flexiblesystem can thus be provided.

3. Embodiment 2

Wireless communication system 1800 according to Embodiment 2 as anotherembodiment of the present disclosure is described below.

3.1 Wireless Communication System 1800

Wireless communication system 1800 includes parent station 1810, APs1820-1, 1820-2, 1820-3, and 1820-4, and terminals 1830-1, 1830-2, . . ., 1830-8, as illustrated in FIG. 18 .

Parent station 1810 is connected to a communication device (notillustrated) directly, or indirectly via a communication line. Thecommunication device is, for example, a broadcast device forbroadcasting data or a distribution system or a server for transmittingdata. The communication device transmits a control signal and data. Thecontrol signal includes unicast transmission-related setting ormulticast transmission-related setting, and phase change method setting.The communication device may include a plurality of communicationdevices. In this case, a first communication device may transmit thecontrol signal, and a second communication device may transmit the data.Parent station 1810 is wiredly (or wirelessly) connected to APs 1820-1,1820-2, 1820-3, and 1820-4. AP 1820-1 is wiredly (or wirelessly)connected to APs 1820-2, 1820-3, and 1820-4.

Parent station 1810 receives the control signal and the data from thecommunication device. Parent station 1810 transmits the control signalto AP 1820-1. Parent station 1810 transmits the data to each of APs1820-1, 1820-2, 1820-3, and 1820-4. APs 1820-1, 1820-2, 1820-3, and1820-4 wirelessly transmit the data obtained from parent station 1810.

Terminals 1830-1, 1830-2, . . . , 1830-8 are each a mobile phone, asmartphone, a tablet, or a personal computer (PC) that has a wirelesscommunication function using a frequency bandwidth of 6 GHz or more suchas millimeter wave, e.g. a frequency bandwidth of 60 GHz. Terminal1830-1, for example, wirelessly receives data from AP 1820-1 in the casewhere terminal 1830-1 is located near AP 1820-1. Terminals 1830-2, . . ., 1830-8 each wirelessly receive data from its nearby AP, as withterminal 1830-1.

Terminal 1830-1 also wirelessly transmits data. In the case whereterminal 1830-1 is located near AP 1820-1, AP 1820-1 wirelessly receivesthe data from terminal 1830-1. AP 1820-1 transmits the received data toparent station 1810.

Terminals 1830-2, 1830-3, . . . , 1830-8 each wirelessly transmit data,as with terminal 1830-1. An AP located near each terminal wirelesslyreceives the data from the terminal. The AP transmits the data receivedfrom the terminal, to parent station 1810.

Parent station 1810 obtains the data transmitted from each terminal, viathe corresponding AP. Parent station 1810 outputs the received data tothe communication device.

The control signal transmitted from parent station 1810 to AP 1820-1includes unicast transmission-related setting or multicasttransmission-related setting in each AP, and phase change method settingin each AP. Parent station 1810 does not perform unicasttransmission-related setting and multicast transmission-related settingfor APs 1820-2, 1820-3, and 1820-4. Parent station 1810 does not performphase change method setting for APs 1820-2, 1820-3, and 1820-4.

AP 1820-1 performs unicast transmission-related setting or multicasttransmission-related setting for APs 1820-2, 1820-3, and 1820-4. AP1820-1 also performs phase change method setting for APs 1820-2, 1820-3,and 1820-4.

AP 1820-1 is called “master AP”. APs 1820-2, 1820-3, and 1820-4 arecalled “non-master AP”.

3.2 AP 1820-1 as Master AP

AP 1820-1 as a master AP includes encoder 202, interleaver 204, mappingunit 206, phase changer 208, wireless unit 210, antenna 212, antenna215, reception device 217, and indicator 1902, as illustrated in FIG. 19.

AP 1820-1 receives control signal 1901 from parent station 1810. Controlsignal 1901 includes unicast transmission-related setting or multicasttransmission-related setting, and phase change method setting.

AP 1820-1 performs unicast transmission-related setting or multicasttransmission-related setting, based on control signal 1901 received fromparent station 1810. AP 1820-1 also performs phase change methodsetting, based on control signal 1901. In the case where multicasttransmission-related setting is performed, the AP is set to use the samefrequency (frequency band) as other APs.

In the case of performing unicast transmission-related setting, AP1820-1 operates reception device 217. In the case of performingmulticast transmission-related setting, AP 1820-1 may stop the operationof reception device 217.

AP 1820-1 performs wireless transmission/reception using the samechannel in the case of unicast and in the case of multicast. Here, AP1820-1 may divide one wireless carrier into several time slots, and useeach time slot as a communication channel. Alternatively, AP 1820-1 mayuse each of a plurality of different frequencies in the frequencybandwidth of 60 GHz, as a communication channel.

(1) Encoder 202

Encoder 202 receives data 201 from parent station 1810. Encoder 202 alsoreceives control signal 213 from a controller included in AP 1820-1.Control signal 213 includes information such as encoding schemedesignation, error correction scheme designation, encoding rate, andblock length. Encoder 202 performs error correction encoding, such asconvolution encoding, LDPC encoding, or turbo encoding, on data 201,using the schemes designated by control signal 213. Encoder 202 outputsencoded data 203.

(2) Interleaver 204

Interleaver 204 receives encoded data 203 from encoder 202. Interleaver204 also receives control signal 213 from the controller included in AP1820-1. Control signal 213 includes interleave method designation.Interleaver 204 performs interleaving, i.e. rearrangement, on encodeddata 203, using the method designated by control signal 213. Interleaver204 outputs interleaved data 205.

(3) Mapping Unit 206

Mapping unit 206 receives interleaved data 205 from interleaver 204.Mapping unit 206 also receives control signal 213 from the controllerincluded in AP 1820-1. Control signal 213 includes modulation schemedesignation. Mapping unit 206 performs modulation, such as quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),or 64 quadrature amplitude modulation (64QAM), on interleaved data 205according to the modulation scheme designation included in controlsignal 213, to generate modulated signal 207. Mapping unit 206 outputsmodulated signal 207. Other modulation schemes may be used.

Mapping unit 206 may perform mapping including a phase change process.

(4) Phase Changer 208

Phase changer 208 receives modulated signal 207 from mapping unit 206.Phase changer 208 also receives control signal 1903_0. Control signal1903_0 includes phase change method setting. Phase changer 208 performsphase change on modulated signal 207 according to the phase changemethod setting included in control signal 1903_0, to generatephase-changed signal 209. Phase changer 208 outputs phase-changed signal209.

(5) Wireless Unit 210 and Antenna 212

Wireless unit 210 receives phase-changed signal 209 from phase changer208. Wireless unit 210 also receives control signal 213 from thecontroller included in AP 1820-1. Control signal 213 includesdesignation of frequency conversion, amplification, etc. Wireless unit210 performs processes such as frequency conversion and amplification onphase-changed signal 209, to generate transmission signal 211. Wirelessunit 210 outputs generated transmission signal 211 to antenna 212, usinga frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz.

Antenna 212 outputs transmission signal 211 as a radio wave.

(6) Antenna 215 and Reception Device 217

Antenna 215 receives signal 216 output from each terminal as a radiowave.

Reception device 217 receives signal 216 from antenna 215 using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz, and performs processes such asamplification and frequency conversion on signal 216, to generate data218. Reception device 217 outputs data 218 to parent station 1810.

Although antennas 212 and 215 are described separately for convenience'ssake, they may be the same entity.

(7) Indicator 1902

Indicator 1902 is connected to parent station 1810.

Indicator 1902 receives control signal 1901 from parent station 1810.Control signal 1901 includes unicast transmission-related setting ormulticast transmission-related setting, and phase change method setting.

Separate control signal 1901 may be set for each AP, or same controlsignal 1901 may be set for all APs.

Indicator 1902 performs multicast transmission-related setting orunicast transmission-related setting for all APs including AP 1820-1,using control signals 19030, 1903_1, . . . , 1903_N.

Here, indicator 1902 may perform multicast transmission-related settingfor all APs, or perform unicast transmission-related setting for allAPs. Indicator 1902 may perform multicast transmission-related settingfor part of the APs, and unicast transmission-related setting for theother APs.

For a plurality of APs subjected to multicast transmission-relatedsetting, the modulated signal before phase change is the same signal. Inother words, the same data is transmitted.

Indicator 1902 also indicates a phase change method to each AP, usingcontrol signals 1903_1, . . . , 1903_N.

For a plurality of APs subjected to unicast transmission-relatedsetting, the modulated signal before phase change may be the same signalor a different signal. In other words, the same data may be transmitted,or different data may be transmitted.

Thus, indicator 1902 generates control signals 1903_0, 1903_1, . . . ,1903_N for the respective APs, from received control signal 1901. Eachcontrol signal includes multicast transmission-related setting orunicast transmission-related setting, and phase change method setting.Indicator 1902 outputs control signals 1903_0, 1903_1, . . . , 1903_N toitself and APs 1820-2, 1820-3, and 1820-4.

In the case of designating unicast transmission for AP 1820-1, indicator1902 operates reception device 217. In the case of designating multicasttransmission for AP 1820-1, indicator 1902 may stop the operation ofreception device 217.

3.3 Non-Master AP 2000

APs 1820-2, 1820-3, and 1820-4 are each a non-master AP. APs 1820-2,1820-3, and 1820-4 are described below, as AP 2000 collectively.

Non-master AP 2000 includes encoder 202, interleaver 204, mapping unit206, phase changer 208, wireless unit 210, antenna 212, antenna 215, andreception device 217, as illustrated in FIG. 20 .

AP 2000 receives control signal 2001_0 from AP 1820-1 which is a masterAP. Control signal 2001_0 includes unicast transmission-related settingor multicast transmission-related setting, and phase change methodsetting. AP 2000 also receives data 2002 from AP 1820-1 which is amaster AP. In the case of performing AP cooperation, AP 2000 may receivedata 2003 from another non-master AP. In the case of operating singly inunicast transmission, AP 2000 may receive data 201 from parent station1810.

AP 2000 performs unicast transmission-related setting or multicasttransmission-related setting, based on control signal 2001_0. AP 2000also performs phase change method setting, based on control signal2001_0. In the case where multicast transmission is set, the AP is setto use the same frequency (frequency band) as other APs.

In the case where unicast transmission is set, AP 2000 operatesreception device 217. In the case where multicast transmission is set,AP 2000 may stop the operation of reception device 217.

AP 2000 performs wireless transmission/reception using the same channel(or the same frequency) in the case of unicast transmission and in thecase of multicast transmission. Here, A P 2000 may divide one wirelesscarrier into several time slots, and use each time slot as acommunication channel. Alternatively, A P 2000 may use each of aplurality of different frequencies in the frequency bandwidth of 60 GHz,as a communication channel.

(1) Encoder 202

Encoder 202 receives data 2002, 2003, or 201. Encoder 202 also receivescontrol signal 213 from a controller included in AP 2000. Control signal213 includes information such as encoding scheme designation, errorcorrection scheme designation, encoding rate, and block length. Encoder202 performs error correction encoding, such as convolution encoding,LDPC encoding, or turbo encoding, on data 2002, 2003, or 201, using theschemes designated by control signal 213. Encoder 202 outputs encodeddata 203.

(2) Interleaver 204

Interleaver 204 receives encoded data 203 from encoder 202. Interleaver204 also receives control signal 213 from the controller included in AP2000. Control signal 213 includes interleave method designation.Interleaver 204 performs interleaving, i.e. rearrangement, on encodeddata 203, using the method designated by control signal 213. Interleaver204 outputs interleaved data 205.

(3) Mapping Unit 206

Mapping unit 206 receives interleaved data 205 from interleaver 204.Mapping unit 206 also receives control signal 213 from the controllerincluded in AP 2000. Control signal 213 includes modulation schemedesignation. Mapping unit 206 performs modulation, such as quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),or 64 quadrature amplitude modulation (64QAM), on interleaved data 205according to the modulation scheme designation included in controlsignal 213, to generate modulated signal 207. Mapping unit 206 outputsmodulated signal 207. Other modulation schemes may be used.

Mapping unit 206 may perform mapping including a phase change process.

(4) Phase Changer 208

Phase changer 208 receives modulated signal 207 from mapping unit 206.Phase changer 208 also receives control signal 2001_0. Control signal2001_0 includes phase change method setting. Phase changer 208 performsphase change on modulated signal 207 according to the phase changemethod setting included in control signal 2001_0, to generatephase-changed signal 209. Phase changer 208 outputs phase-changed signal209.

(5) Wireless Unit 210 and Antenna 212

Wireless unit 210 receives phase-changed signal 209 from phase changer208. Wireless unit 210 also receives control signal 213 from thecontroller included in AP 2000. Control signal 213 includes designationof frequency conversion, amplification, etc. Wireless unit 210 performsprocesses such as frequency conversion and amplification onphase-changed data 209, to generate transmission data 211. Wireless unit210 outputs generated transmission signal 211 to antenna 212, using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz.

Antenna 212 outputs transmission signal 211 as a radio wave.

(6) Antenna 215 and Reception Device 217

Antenna 215 receives signal 216 output from each terminal as a radiowave.

Reception device 217 receives data 216 from antenna 215 using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz, and performs processes such asamplification and frequency conversion on signal 216, to generate data218. Reception device 217 outputs data 218 to parent station 1810.

Although antennas 212 and 215 are described separately for convenience'ssake, they may be the same entity.

3.4 Example of Transmitted Data

An example of data transmitted by parent station 1810 and APs 1820-1,1820-2, 1820-3, and 1820-4 is described below.

(1) In the Case of Setting all APs for Multicast to Transmit Data

An example of transmitted data in the case of setting all APs 1820-1,1820-2, 1820-3, and 1820-4 for multicast to transmit data is describedbelow, with reference to FIG. 21 .

Parent station 1810 receives packets 2101, 2102, 2103, 2104, . . . inthis order, as illustrated in FIG. 21 . Packets 2101, 2102, 2103, 2104,. . . are all multicast packets. Packets 2101, 2102, 2103, 2104, . . .are generated from one set of multicast data. Parent station 1810transmits packets 2101, 2102, 2103, 2104, . . . in this order, to AP1820-1.

AP 1820-1 receives packets 2101, 2102, 2103, 2104, . . . in this order.AP 1820-1 then transmits packets 2101, 2102, 2103, 2104, . . . in thisorder, to APs 1820-2, 1820-3, and 1820-4.

AP 1820-1 receives packets 2101, 2102, 2103, 2104, . . . in this order.Upon receiving packets 2101, 2102, 2103, 2104, . . . in this order, AP1820-1 wirelessly outputs packets 2106, 2107, 2108, 2109, . . . in thisorder, in multicast transmission. Packets 2101, 2102, 2103, 2104, . . .respectively correspond to packets 2106, 2107, 2108, 2109.

Upon receiving packets 2101, 2102, 2103, 2104, . . . in this order, AP1820-2 wirelessly outputs packets 2111, 2112, 2113, 2114, . . . in thisorder, in multicast transmission. Packets 2101, 2102, 2103, 2104, . . .respectively correspond to packets 2111, 2112, 2113, 2114.

Upon receiving packets 2101, 2102, 2103, 2104, . . . in this order, AP1820-3 wirelessly outputs packets 2116, 2117, 2118, 2119, . . . in thisorder, in multicast transmission. Packets 2101, 2102, 2103, 2104, . . .respectively correspond to packets 2116, 2117, 2118, 2119.

Upon receiving packets 2101, 2102, 2103, 2104, . . . in this order, AP1820-4 wirelessly outputs packets 2121, 2122, 2123, 2124, . . . in thisorder, in multicast transmission. Packets 2101, 2102, 2103, 2104, . . .respectively correspond to packets 2121, 2122, 2123, 2124.

In this case, a feature lies in that APs 1820-1, 1820-2, 1820-3, and1820-4 each perform phase change on the modulated signal (alternatively,any of APs 1820-1, 1820-2, 1820-3, and 1820-4 may perform no phasechange).

This has the advantages of widening the cell range within the reach of amulticast modulated signal, and reducing, by means of phase change,points at which reception is difficult due to modulated signalinterference.

(2) In the Case of Setting Two APs for Multicast to Transmit Data

An example of transmitted data in the case of setting two APs 1820-1 and1820-2 for multicast transmission and other two APs 1820-3 and 1820-4for unicast transmission to transmit data is described below, withreference to FIG. 22 . In this case, APs 1820-1 and 1820-2 transmit thesame data (the modulated signal after mapping and before phase change isthe same). Moreover, APs 1820-3 and 1820-4 transmit the same data (themodulated signal after mapping and before phase change is the same).

Parent station 1810 receives packets 2201, 2202, 2203, 2204, 2205, 2206,. . . in this order, as illustrated in FIG. 22 . Packets 2201, 2203,2204, and 2206 are multicast packets. Packets 2202 and 2205 are unicastpackets. Packets 2201, 2203, 2204, and 2206 are generated from one setof multicast data. Packets 2202 and 2205 are generated from one set ofunicast data.

Upon receiving packets 2201, 2202, 2203, 2204, 2205, 2206, . . . in thisorder, parent station 1810 transmits packets 2201, 2202, 2203, 2204,2205, 2206, . . . in this order, to AP 1820-1.

Upon receiving packets 2201, 2202, 2203, 2204, 2205, 2206, . . . , AP1820-1 transmits multicast packets 2201, 2203, 2204, 2206, . . . to itsencoder 202, and multicast packets 2201, 2203, 2204, 2206, . . . to AP1820-2. AP 1820-1 transmits unicast packets 2202, 2205, . . . to APs1820-3 and 1820-4.

Upon receiving packets 2201, 2203, 2204, and 2206, AP 1820-1 wirelesslyoutputs packets 2211, 2212, 2213, and 2214, in multicast transmission.Packets 2201, 2203, 2204, and 2206 respectively correspond to packets2211, 2212, 2213, and 2214.

Upon receiving packets 2201, 2203, 2204, and 2206, AP 1820-2 wirelesslyoutputs packets 2221, 2222, 2223, and 2224, in multicast transmission.Packets 2201, 2203, 2204, and 2206 respectively correspond to packets2221, 2222, 2223, and 2224.

Upon receiving packets 2202 and 2205, AP 1820-3 wirelessly outputspackets 2231 and 2232, in unicast transmission. Packets 2202 and 2205respectively correspond to packets 2231 and 2232.

Upon receiving packets 2202 and 2205, AP 1820-4 wirelessly outputspackets 2241 and 2242, in unicast transmission. Packets 2202 and 2205respectively correspond to packets 2241 and 2242.

As described above, in the case of transmitting the modulated signal inunicast transmission, the packets transmitted in APs 1820-3 and 1820-4are based on the same data. Here, APs 1820-3 and 1820-4 have the sametransmission parameter. APs 1820-3 and 1820-4 may perform differentphase changes (alternatively, any of APs 1820-3 and 1820-4 may performno phase change).

This has the advantages of widening the cell range within the reach of aunicast modulated signal, and reducing, by means of phase change, pointsat which reception is difficult due to modulated signal interference.

A feature lies in that APs 1820-1 and 1820-2 each perform phase changeon the modulated signal (alternatively, any of APs 1820-1 and 1820-2 mayperform no phase change). (The phase change method will be described indetail later.)

This has the advantages of widening the cell range within the reach of amulticast modulated signal, and reducing, by means of phase change,points at which reception is difficult due to modulated signalinterference.

(3) In the Case of Setting Two APs for Multicast to Transmit Data

An example of transmitted data in the case of setting two APs 1820-1 and1820-2 for multicast transmission and other two APs 1820-3 and 1820-4for unicast transmission to transmit data is described below, withreference to FIG. 23 . In FIG. 23 , APs 1820-3 and 1820-4 transmitdifferent data.

Parent station 1810 receives packets 2301, 2302, 2303, 2304, 2305, 2306,2307, 2308, 2309, 2310, . . . in this order, as illustrated in FIG. 23 .Packets 2301, 2303, 2304, and 2306 are multicast packets. Packets 2302,2307, and 2309 are unicast packets transmitted by AP 1820-3. Packets2305, 2308, and 2310 are unicast packets transmitted by AP 1820-4.

Packets 2301, 2303, 2304, and 2306 are generated from one set ofmulticast data. Packets 2302, 2307, and 2309 are generated from one setof unicast data. Packets 2305, 2308, and 2310 are generated from anotherset of unicast data.

Upon receiving packets 2301, 2302, 2303, 2304, 2305, 2306, 2307, 2308,2309, 2310, . . . in this order, parent station 1810 transmits multicastpackets 2301, 2303, 2304, and 2306 to APs 1820-1 and 1820-2.

Upon receiving packets 2301, 2303, 2304, and 2306, AP 1820-1 wirelesslyoutputs packets 2321, 2322, 2323, and 2324, in multicast transmission.Packets 2301, 2303, 2304, and 2306 respectively correspond to packets2321, 2322, 2323, and 2324.

Upon receiving packets 2301, 2303, 2304, and 2306, AP 1820-2 wirelesslyoutputs packets 2325, 2326, 2327, and 2328, in multicast transmission.Packets 2301, 2303, 2304, and 2306 respectively correspond to packets2325, 2326, 2327, and 2328.

Upon receiving packets 2301, 2302, 2303, 2304, 2305, 2306, 2307, 2308,2309, 2310, . . . in this order, parent station 1810 transmits unicastpackets 2302, 2307, and 2309 to AP 1820-3.

Upon receiving packets 2302, 2307, and 2309, AP 1820-3 wirelesslyoutputs packets 2331, 2332, and 2333, in unicast transmission. Packets2302, 2307, and 2309 respectively correspond to packets 2331, 2332, and2333.

Upon receiving packets 2301, 2302, 2303, 2304, 2305, 2306, 2307, 2308,2309, 2310, . . . in this order, parent station 1810 transmits unicastpackets 2305, 2308, and 2310 to AP 1820-4.

Upon receiving packets 2305, 2308, and 2310, AP 1820-4 wirelesslyoutputs packets 2341, 2342, and 2343, in unicast transmission. Packets2305, 2308, and 2310 respectively correspond to packets 2341, 2342, and2343.

A feature lies in that APs 1820-1 and 1820-2 each perform phase changeon the modulated signal (alternatively, any of APs 1820-1 and 1820-2 mayperform no phase change).

This has the advantages of widening the cell range within the reach of amulticast modulated signal, and reducing, by means of phase change,points at which reception is difficult due to modulated signalinterference.

Moreover, a flexible system in which APs 1820-3 and 1820-4 can performunicast communication is realized.

There is thus the advantage of realizing a flexible system by, forexample, switching the transmission state among the transmission statein FIG. 21 , the transmission state in FIG. 22 , and the transmissionstate in FIG. 23 depending on time (e.g. switching depending on theterminal presence situation).

3.5 Operation in the Case where Master AP Newly Places AP Under Control

Operation in the case where AP 1820-1 which is a master AP newly placesan AP under control in wireless communication system 1800 is describedbelow, with reference to a flowchart in FIG. 24 .

Suppose three APs 1820-2, 1820-3, and 1820-4 are under control of AP1820-1 which is a master AP, and then a new AP is to be added. At thispoint, the phase change patterns (and (AP) IDs (identification)) havealready been set for four APs 1820-1, 1820-2, 1820-3, and 1820-4.

An AP that intends to be newly placed under control of AP 1820-1notifies AP 1820-1 of a request to be placed under control of parentstation 110. AP 1820-1 receives the request from the new AP (StepS2401).

AP 1820-1 determines whether or not to place the new AP under itscontrol (Step S2402). In the case of determining to place the new APunder its control (Step S2402: “Yes”), AP 1820-1 assigns an ID to thenew AP. Here, the ID is associated with a phase change pattern. The newAP sets the phase change pattern from the assigned ID (Step S2403). Thiscompletes the operation in the case of newly placing an AP undercontrol.

In the case of determining not to place the new AP under its control(Step S2402: “No”), AP 1820-1 notifies the new AP that the AP is not tobe placed under its control (Step S2404). This completes the operationin the case of newly placing an AP under control.

Step S2403 may be performed as follows.

AP 1820-1 which is a master AP transmits information indicating thephase change pattern to be set by the new AP, to the new AP. The new APreceives the information indicating the phase change pattern, and setsthe phase change pattern in the AP based on the received informationindicating the phase change pattern. Here, AP 1820-1 which is a masterAP may or may not assign the ID to the new AP. Assigning the ID here hasthe advantage that, in the case where AP 1820-1 which is a master APdesignates the AP newly placed under its control as a unicasttransmission AP or a multicast transmission AP, the ID and unicasttransmission or multicast transmission can be easily designated for theAP by transmitting information “ID and unicast or multicast” to the AP.

The above describes the case where three APs 1820-2, 1820-3, and 1820-4are under control of AP 1820-1 which is a master AP and then a new AP isto be added. However, this is not a limitation.

There may be no AP under control of AP 1820-1 which is a master AP in aninitial state. In such a case, APs may be placed under control of AP1820-1 which is a master AP one by one, as described above.

In Step S2402, AP 1820-1 which is a master AP may determine whether ornot to place the new AP under its control, depending on a limit to thenumber of APs placed under its control. AP 1820-1 stores a maximum valueof the number of APs placed under its control. When there is a requestfrom one AP to be newly placed under its control, AP 1820-1 adds “1” tothe number of APs currently under its control, and compares the obtainedvalue with the maximum value. In the case where the obtained value isnot greater than the maximum value, AP 1820-1 permits the AP to be underits control. In the case where the obtained value is greater than themaximum value, AP 1820-1 does not permit the AP to be under its control.

In Step S2402, AP 1820-1 may determine whether or not to place the newAP under its control, depending on the position of the new AP and thephase change pattern.

For example, when the new AP is away from AP 1820-1 and each AP alreadyunder its control, AP 1820-1 permits the new AP to be under its control.

For example, when the new AP is near AP 1820-1 or any AP already underits control, if there is a phase change pattern to be assigned to thenew AP, AP 1820-1 permits the new AP to be under its control.

For example, when the new AP is near AP 1820-1 or any AP already underits control, if there is no phase change pattern to be assigned to thenew AP, AP 1820-1 does not permit the new AP to be under its control.

3.6 Conclusion

According to this embodiment, large-capacity transmission of Gbps levelcan be achieved. Moreover, the number of terminals accommodated in thecase of implementing multicast can be increased. Furthermore, unicastcommunication can be realized simultaneously with multicast. A flexiblesystem can thus be provided.

4. Embodiment 3

Wireless communication system 2500 according to Embodiment 3 of thepresent disclosure is described below.

4.1 Wireless Communication System 2500

Wireless communication system 2500 includes parent station 2510, APs2520-1, 2520-2, 2520-3, and 2520-4, and terminals 2530-1, 2530-2, . . ., 2530-8, as illustrated in FIG. 25 .

Parent station 2510 is connected to a communication device (notillustrated) directly, or indirectly via a communication line. Thecommunication device is, for example, a broadcast device forbroadcasting data or a distribution system or a server for transmittingdata. The communication device transmits a control signal and data. Thecontrol signal includes unicast transmission method-related setting ormulticast transmission method-related setting, and weighting methodsetting. The communication device may include a plurality ofcommunication devices. In this case, a first communication device maytransmit the control signal, and a second communication device maytransmit the data. Parent station 2510 is wiredly (or wirelessly)connected to APs 2520-1, 2520-2, 2520-3, and 2520-4.

Parent station 2510 receives the control signal and the data from thecommunication device. Parent station 2510 transmits the control signaland the data to each of APs 2520-1, 2520-2, 2520-3, and 2520-4. APs2520-1, 2520-2, 2520-3, and 2520-4 wirelessly transmit the data obtainedfrom parent station 2510.

Terminals 2530-1, 2530-2, . . . , 2530-8 are each a mobile phone, asmartphone, a tablet, or a personal computer (PC) that has a wirelesscommunication function using a frequency bandwidth of 6 GHz or more suchas millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Terminal 2530-1, for example, wirelessly receives data from AP 2520-1 inthe case where terminal 2530-1 is located near AP 2520-1. Terminals2530-2, . . . , 2530-8 each wirelessly receive data from its nearby AP,as with terminal 2530-1.

Terminal 2530-1 also wirelessly transmits data. In the case whereterminal 2530-1 is located near AP 2520-1, AP 2520-1 wirelessly receivesthe data from terminal 2530-1. AP 2520-1 transmits the received data toparent station 2510.

Terminals 2530-2, 2530-3, . . . , 2530-8 each wirelessly transmit data,as with terminal 2530-1. An AP located near each terminal wirelesslyreceives the data from the terminal. The AP transmits the data receivedfrom the terminal, to parent station 2510.

Parent station 2510 receives data from each terminal via a correspondingAP. Parent station 2510 outputs the received data to the communicationdevice.

The control signal transmitted from parent station 2510 to APs 2520-1,2520-2, 2520-3, and 2520-4 includes unicast transmission-related settingor multicast transmission-related setting in each AP, and weightingmethod setting in each AP.

4.2 AP 2520

APs 2520-1, 2520-2, 2520-3, and 2520-4, for example, have the samestructure (same function). APs 2520-1, 2520-2, 2520-3, and 2520-4 aredescribed below, as AP 2520 collectively.

AP 2520 includes encoder 202, interleaver 204, mapping unit 206,weighting unit 2601, wireless unit 210, antenna 212, antenna 215, andreception device 217, as illustrated in FIG. 26 .

AP 2520 receives control signal 214 from parent station 2510. Controlsignal 214 includes unicast transmission method-related setting ormulticast transmission method-related setting, and weighting methodsetting.

AP 2520 performs unicast transmission method-related setting ormulticast transmission-related setting, based on control signal 214received from parent station 2510. AP 2520 also performs weightingmethod setting, based on control signal 214. In the case where multicasttransmission is set, the AP is set to use the same frequency (frequencyband) as other APs.

In the case where unicast transmission is set, AP 2520 operatesreception device 217. In the case where multicast transmission is set,AP 2520 may stop the operation of reception device 217.

AP 2520 performs wireless transmission/reception using the same channel(or the same frequency (frequency band)) in the case of unicasttransmission and in the case of multicast transmission. Here, AP 2520may divide one wireless carrier into several time slots, and use eachtime slot as a communication channel. Alternatively, AP 2520 may useeach of a plurality of different frequencies in the frequency bandwidthof 60 GHz, as a communication channel.

(1) Encoder 202

Encoder 202 receives data 201 from parent station 2510. Encoder 202 alsoreceives control signal 213 from a controller included in AP 2520.Control signal 213 includes information such as encoding schemedesignation, error correction scheme designation, encoding rate, andblock length. Encoder 202 performs error correction encoding, such asconvolution encoding, LDPC encoding, or turbo encoding, on data 201,using the schemes designated by control signal 213. Encoder 202 outputsencoded data 203.

(2) Interleaver 204

Interleaver 204 receives encoded data 203 from encoder 202. Interleaver204 also receives control signal 213 from the controller included in AP2520. Control signal 213 includes interleave method designation.Interleaver 204 performs interleaving, i.e. rearrangement, on encodeddata 203, using the method designated by control signal 213. Interleaver204 outputs interleaved data 205.

(3) Mapping Unit 206

Mapping unit 206 receives interleaved data 205 from interleaver 204.Mapping unit 206 also receives control signal 213 from the controllerincluded in AP 2520. Control signal 213 includes modulation schemedesignation. Mapping unit 206 performs modulation, such as quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),or 64 quadrature amplitude modulation (64QAM), on interleaved data 205according to the modulation scheme designation included in controlsignal 213, to generate modulated signal 207. Mapping unit 206 outputsmodulated signal 207. Other modulation schemes may be used.

Mapping unit 206 may perform mapping including a weighting process.

(4) Weighting Unit 2601

Weighting unit 2601 receives modulated signal 207 from mapping unit 206.Weighting unit 2601 also receives control signal 214. Control signal 214includes weighting method setting. Weighting unit 2601 performsweighting on modulated signal 207 according to the weighting methodsetting included in control signal 214, to generate weighted signal2602. Weighting unit 2601 outputs weighted signal 2602.

(5) Wireless Unit 210 and Antenna 212

Wireless unit 210 receives weighted data 2602 from weighting unit 2601.Wireless unit 210 also receives control signal 213 from the controllerincluded in AP 2520. Control signal 213 includes designation offrequency conversion, amplification, etc. Wireless unit 210 performsprocesses such as frequency conversion and amplification on weightedsignal 2602, to generate transmission signal 211. Wireless unit 210outputs generated transmission signal 211 to antenna 212, using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz.

Antenna 212 outputs transmission signal 211 as a radio wave.

(6) Antenna 215 and Reception Device 217

Antenna 215 receives signal 216 output from each terminal as a radiowave.

Reception device 217 receives signal 216 from antenna 215 using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz, and performs processes such asamplification and frequency conversion on signal 216, to generate data218. Reception device 217 outputs data 218 to parent station 2510.

Although antennas 212 and 215 are described separately for convenience'ssake, they may be the same entity.

4.3 Parent Station 2510

Parent station 2510 includes transmission data separator 302, receptiondata separator 305, and indicator 308, as illustrated in FIG. 27 .

(1) Indicator 308

Indicator 308 is connected to the communication device and APs 2520-1,2520-2, 2520-3, and 2520-4.

Indicator 308 receives control signal 307. Control signal 307 includesunicast transmission-related setting or multicast transmission-relatedsetting, and weighting method setting. For example, the communicationdevice includes a PC, and the user of the PC inputs the control signalthrough the PC.

Separate control signal 307 may be set for each AP, or same controlsignal 307 may be set for all APs.

Multicast transmission may be set for all APs, or unicast transmissionmay be set for all APs. Multicast transmission may be set for part ofthe APs, and unicast transmission for the other APs. Thus, multicasttransmission-related setting and unicast-related setting may be mixedfor the APs.

For a plurality of APs set for multicast, the modulated signal beforeweighting is the same signal. In other words, the same data istransmitted.

Indicator 308 also indicates a weighting method to each AP.

For a plurality of APs set for unicast, the modulated signal beforeweighting may be the same signal or a different signal. In other words,the same data may be transmitted, or different data may be transmitted.

Indicator 308 outputs received control signal 307 to transmission dataseparator 302, reception data separator 305, and APs 2520-1, 2520-2,2520-3, and 2520-4.

(2) Transmission Data Separator 302

Transmission data separator 302 is connected to the communicationdevice, indicator 308, and APs 2520-1, 2520-2, 2520-3, and 2520-4.

Transmission data separator 302 receives control signal 310 fromindicator 308. Transmission data separator 302 outputs received controlsignal 310 to APs 2520-1, 2520-2, 2520-3, and 2520-4.

Transmission data separator 302 also receives data 301 from thecommunication device. Transmission data separator 302 separates thereceived data into data for AP 2520-1, data for AP 2520-2, data for AP2520-3, and data for AP 2520-4. Transmission data separator 302 outputsthe separated data to each of APs 2520-1, 2520-2, 2520-3, and 2520-4.

(3) Reception Data Separator 305

Reception data separator 305 is connected to the communication device,indicator 308, and APs 2520-1, 2520-2, 2520-3, and 2520-4.

Reception data separator 305 receives data 304-1, 304-2, 304-3, and304-4 respectively from APs 2520-1, 2520-2, 2520-3, and 2520-4.Reception data separator 305 outputs received data 304-1, 304-2, 304-3,and 304-4 to the communication device.

4.4 Example of transmitted data

An example of data transmitted by parent station 2510 and APs 2520-1,2520-2, 2520-3, and 2520-4 is described below.

(1) In the Case of Setting all APs for Multicast Transmission toTransmit Data

An example of transmitted data in the case of setting all APs 2520-1,2520-2, 2520-3, and 2520-4 for multicast transmission to transmit datais described below, with reference to FIGS. 28 and 29 .

Transmission data separator 302 receives packets 2811, 2812, 2813, 2814,. . . in this order, as illustrated in FIG. 28 . Packets 2811, 2812,2813, 2814, . . . are all multicast packets. Packets 2811, 2812, 2813,2814, . . . are generated from one set of multicast data.

Transmission data separator 302 outputs packets 2811, 2812, 2813, 2814,. . . in this order, to each of APs 2520-1, 2520-2, 2520-3, and 2520-4.

(a) Process 1 of Each AP

As illustrated in FIGS. 25 and 28 , AP 2520-1 prepares A1(0), A1(1),A1(2), A1(3), . . . as weights. Likewise, AP 2520-2 prepares A2(0),A2(1), A2(2), A2(3), . . . as weights. AP 2520-3 prepares A3(0), A3(1),A3(2), A3(3), . . . as weights. AP 2520-4 prepares A4(0), A4(1), A4(2),A4(3), . . . as weights.

(b) Process 2 of Each AP

The process of each AP is described below, with reference to FIG. 29 .

(Process of AP 2520-1)

Mapping unit 206 in AP 2520-1 generates mapped baseband signal complexnumbers (which may be real numbers) 2911 “c(0)”, 2912 “c(1)”, 2913“c(2)”, 2914 “c(3)”, . . . , as illustrated in FIG. 29 .

c(0) is a mapped baseband signal related to packet 2811, c(1) is amapped baseband signal related to packet 2812, c(2) is a mapped basebandsignal related to packet 2813, c(3) is a mapped baseband signal relatedto packet 2814, . . . .

After mapped baseband signal complex number 2911 “c(0)” is generated,weighting unit 2601 in AP 2520-1 calculates c(0)×A1(0) (2931),c(0)×A1(1) (2932), c(0)×A1(2) (2933), and c(0)×A1(3) (2934), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 2520-1 wirelessly outputs c(0)×A1(0) (2931), c(0)×A1(1) (2932),c(0)×A1(2) (2933), and c(0)×A1(3) (2934).

After mapped baseband signal complex number 2912 “c(1)” is generated,weighting unit 2601 in AP 2520-1 calculates c(1)×A1(0) (2935),c(1)×A1(1) (2936), c(1)×A1(2) (2937), and c(1)×A1(3) (2938), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 2520-1 wirelessly outputs c(1)×A1(0) (2935), c(1)×A1(1) (2936),c(1)×A1(2) (2937), and c(1)×A1(3) (2938).

In the case where mapped baseband signal complex numbers 2913 “c(2)”,2914 “c(3)”, . . . are generated, AP 2520-1 operates in the same way asabove.

(Process of AP 2520-2)

Mapping unit 206 in AP 2520-2 generates mapped baseband signal complexnumbers 2911 “c(0)”, 2912 “c(1)”, 2913 “c(2)”, 2914 “c(3)”, . . . , asillustrated in FIG. 29 .

c(0) is a mapped baseband signal related to packet 2811, c(1) is amapped baseband signal related to packet 2812, c(2) is a mapped basebandsignal related to packet 2813, c(3) is a mapped baseband signal relatedto packet 2814, . . . .

After mapped baseband signal complex number 2911 “c(0)” is generated,weighting unit 2601 in AP 2520-2 calculates c(0)×A2(0) (2941),c(0)×A2(1) (2942), c(0)×A2(2) (2943), and c(0)×A2(3) (2944), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 2520-2 wirelessly outputs c(0)×A2(0) (2941), c(0)×A2(1) (2942),c(0)×A2(2) (2943), and c(0)×A2(3) (2944).

After mapped baseband signal complex number 2912 “c(1)” is generated,weighting unit 2601 in AP 2520-2 calculates c(1)×A2(0) (2945),c(1)×A2(1) (2946), c(1)×A2(2) (2947), and c(1)×A2(3) (2948), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 2520-2 wirelessly outputs c(1)×A2(0) (2945), c(1)×A2(1) (2946),c(1)×A2(2) (2947), and c(1)×A2(3) (2948).

In the case where mapped baseband signal complex numbers 2913 “c(2)”,2914 “c(3)”, . . . are generated, AP 2520-2 operates in the same way asabove.

(Process of APs 2520-3 and 2520-4)

APs 2520-3 and 2520-4 operate in the same way as above.

Here, weighting unit 2601 in AP 2520-3 performs weighting using complexnumbers A3(0), A3(1), A3(2), and A3(3).

Moreover, weighting unit 2601 in AP 2520-4 performs weighting usingcomplex numbers A4(0), A4(1), A4(2), and A4(3).

Thus, features lie in that each packet is subjected to differentweighting and transmitted a plurality of times, and that each packet istransmitted a plurality of times from a plurality of APs.

Transmission using a plurality of APs has the advantageous effect ofwidening the cell area. In addition, transmitting each packet aplurality of times with different weighting has the advantageous effectof maintaining more uniform reception quality in the cell area becausethe packet is transmitted a plurality of times with differentdirectivity.

For example, weighting coefficients A1(i), A2(i), A3(i), and A4(i) havethe following properties.

-   -   Suppose a modulated signal of packet A is transmitted N times (N        is an integer greater than or equal to 2). Let A1(u) be a        weighting coefficient used to transmit the u-th modulated signal        of packet A, and A1(v) be a weighting coefficient used to        transmit the v-th modulated signal of packet A. u and v are each        an integer greater than or equal to 1 and less than or equal to        N, where u≠v. For all u and v that are each an integer greater        than or equal to 1 and less than or equal to N where u≠v,        A1(u)≠A1(v) holds.    -   Equally suppose a modulated signal of packet A is transmitted N        times (N is an integer greater than or equal to 2). Let Ak(u) be        a weighting coefficient used to transmit the u-th modulated        signal of packet A, and Ak(v) be a weighting coefficient used to        transmit the v-th modulated signal of packet A. u and v are each        an integer greater than or equal to 1 and less than or equal to        N, where u≠v. For all u and v that are each an integer greater        than or equal to 1 and less than or equal to N where u≠v,        Ak(u)≠Ak(v) holds (k is an integer greater than or equal to 1).    -   Weighting coefficient Ak(i) may have a cycle. When the cycle is        denoted by M (M is an integer greater than or equal to 2), the        following Expression (8) holds.

[Math. 8]

Ak(i)=Ak(i mod M)  Expression (8).

i mod M is the remainder after division of i by M.

(2) In the Case of Setting APs 2520-1 and 2520-2 for MulticastTransmission and APs 2520-3 and 2520-4 for Unicast Transmission toTransmit Data

An example of transmitted data in the case of setting APs 2520-1 and2520-2 for multicast transmission and APs 2520-3 and 2520-4 for unicasttransmission to transmit data is described below, with reference toFIGS. 30 and 31 . In this case, APs 2520-1 and 2520-2 transmit the samedata (the modulated signal after mapping and before phase change is thesame). Moreover, APs 2520-3 and 2520-4 transmit the same data (themodulated signal after mapping is the same).

Transmission data separator 302 receives packets 3011, 3012, 3013, 3014,. . . in this order, as illustrated in FIG. 30 . Packets 3011, 3013,3014, 3016, . . . are multicast packets. Packets 3011, 3013, 3014, 3016,. . . are generated from one set of multicast data. Packets 3012, 3015,. . . are unicast packets. Packets 3012, 3015, . . . are generated fromone set of unicast data.

Transmission data separator 302 outputs multicast packets 3011, 3013,3014, 3016, . . . in this order, to each of APs 2520-1 and 2520-2.Transmission data separator 302 also outputs unicast packets 3012, 3015,. . . in this order, to each of APs 2520-3 and 2520-4.

(a) Process 1 of each AP

As illustrated in FIGS. 25 and 30 , AP 2520-1 prepares A1(0), A1(1),A1(2), A1(3), . . . as weights. Likewise, AP 2520-2 prepares A2(0),A2(1), A2(2), A2(3), . . . as weights.

(b) Process 2 of Each AP

Another example of the process of each AP is described below, withreference to FIG. 31 .

(Process of AP 2520-1)

Mapping unit 206 in AP 2520-1 generates mapped baseband signal complexnumbers 3111 “c(0)”, 3112 “c(1)”, 3113 “c(2)”, 3114 “c(3)”, . . . , asillustrated in FIG. 31 .

c(0) is a mapped baseband signal related to packet 3011, c(1) is amapped baseband signal related to packet 3013, c(2) is a mapped basebandsignal related to packet 3014, c(3) is a mapped baseband signal relatedto packet 3016, . . . .

After mapped baseband signal complex number 3111 “c(0)” is generated,weighting unit 2601 in AP 2520-1 calculates c(0)×A1(0) (3131),c(0)×A1(1) (3132), c(0)×A1(2) (3133), and c(0)×A1(3) (3134), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 2520-1 wirelessly outputs c(0)×A1(0) (3131), c(0)×A1(1) (3132),c(0)×A1(2) (3133), and c(0)×A1(3) (3134).

After mapped baseband signal complex number 3112 “c(1)” is generated,weighting unit 2601 in AP 2520-1 calculates c(1)×A1(0) (3135),c(1)×A1(1) (3136), c(1)×A1(2) (3137), and c(1)×A1(3) (3138), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 2520-1 wirelessly outputs c(1)×A1(0) (3135), c(1)×A1(1) (3136),c(1)×A1(2) (3137), and c(1)×A1(3) (3138).

In the case where mapped baseband signal complex numbers 3113 “c(2)”,3114 “c(3)”, . . . are generated, AP 2520-1 operates in the same way asabove.

(Process of AP 2520-2)

Mapping unit 206 in AP 2520-2 generates mapped baseband signal complexnumbers 3111 “c(0)”, 3112 “c(1)”, 3113 “c(2)”, 3114 “c(3)”, . . . , asillustrated in FIG. 31 .

c(0) is a mapped baseband signal related to packet 3011, c(1) is amapped baseband signal related to packet 3013, c(2) is a mapped basebandsignal related to packet 3014, c(3) is a mapped baseband signal relatedto packet 3016, . . . .

After mapped baseband signal complex number 3111 “c(0)” is generated,weighting unit 2601 in AP 2520-2 calculates c(0)×A2(0) (3141),c(0)×A2(1) (3142), c(0)×A2(2) (3143), and c(0)×A2(3) (3144), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 2520-2 wirelessly outputs c(0)×A2(0) (3141), c(0)×A2(1) (3142),c(0)×A2(2) (3143), and c(0)×A2(3) (3144).

After mapped baseband signal complex number 3112 “c(1)” is generated,weighting unit 2601 in AP 2520-2 calculates c(1)×A2(0) (3145),c(1)×A2(1) (3146), c(1)×A2(2) (3147), and c(1)×A2(3) (3148), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 2520-2 wirelessly outputs c(1)×A2(0) (3145), c(1)×A2(1) (3146),c(1)×A2(2) (3147), and c(1)×A2(3) (3148).

In the case where mapped baseband signal complex numbers 3113 “c(2)”,3114 “c(3)”, . . . are generated, AP 2520-2 operates in the same way asabove.

(Process of AP 2520-3)

Mapping unit 206 in AP 2520-3 generates mapped baseband signal complexnumbers “d(0)”, “d(1)”, “d(2)”, . . . d(0) is a mapped baseband signalrelated to packet 3051, d(1) is a mapped baseband signal related topacket 3052, d(2) is a mapped baseband signal related to packet 3053, .. . .

After mapped baseband signal complex number “d(0)” is generated, AP2520-3 wirelessly outputs mapped baseband signal complex number “d(0)”(3151), as illustrated in FIG. 31 .

After mapped baseband signal complex number “d(1)” is generated, AP2520-3 wirelessly outputs mapped baseband signal complex number “d(u)”(3152), as illustrated in FIG. 31 .

Likewise, AP 2520-3 generates mapped baseband signal complex numbers“d(2)”, “d(3)”, “d(4)”, . . . , “d(7)”, . . . , and wirelessly outputsgenerated “d(2)”, “d(3)”, “d(4)”, . . . , “d(7)”, . . . , as illustratedin FIG. 31 .

(Process of AP 2520-4)

Mapping unit 206 in AP 2520-4 generates mapped baseband signal complexnumbers “d(0)”, “d(1)”, “d(2)”, . . . d(0) is a mapped baseband signalrelated to packet 3061, d(1) is a mapped baseband signal related topacket 3062, d(2) is a mapped baseband signal related to packet 3063, .. . .

After mapped baseband signal complex number “d(0)” is generated, AP2520-4 wirelessly outputs mapped baseband signal complex number “d(0)”(3161), as illustrated in FIG. 31 .

After mapped baseband signal complex number “d(1)” is generated, AP2520-4 wirelessly outputs mapped baseband signal complex number “d(1)”(3162), as illustrated in FIG. 31 .

Likewise, AP 2520-4 generates mapped baseband signal complex numbers“d(2)”, “d(3)”, “d(4)”, . . . , “d(7)”, . . . , and wirelessly outputsgenerated “d(2)”, “d(3)”, “d(4)”, . . . , “d(7)”, . . . , as illustratedin FIG. 31 .

Thus, features lie in that each multicast packet is subjected todifferent weighting and transmitted a plurality of times, and that eachmulticast packet is transmitted a plurality of times from a plurality ofAPs.

Transmission using a plurality of APs has the advantageous effect ofwidening the cell area. In addition, transmitting each multicast packeta plurality of times with different weighting has the advantageouseffect of maintaining more uniform reception quality in the cell areabecause the packet is transmitted a plurality of times with differentdirectivity.

In APs 2520-3 and 2520-4, phase change may be performed or weighting maybe changed with respect to time or frequency. This has the advantageouseffect of improving unicast packet reception quality.

(3) In the Case of Setting APs 2520-1 and 2520-2 for Multicast and APs2520-3 and 2520-4 for Unicast to Transmit Data

An example of transmitted data in the case of setting APs 2520-1 and2520-2 for multicast transmission and APs 2520-3 and 2520-4 for unicasttransmission to transmit data is described below, with reference toFIGS. 32 and 33 . In this case, APs 2520-3 and 2520-4 transmit differentdata.

Transmission data separator 302 receives packets 3211, 3212, 3213, 3214,. . . in this order, as illustrated in FIG. 32 . Packets 3211, 3213,3214, 3216, . . . are multicast packets. Packets 3211, 3213, 3214, 3216,. . . are generated from one set of multicast data. Packets 3212, . . .are first unicast packets. Packets 3212, . . . are generated from firstunicast data. Packets 3215, . . . are second unicast packets. Packets3215, . . . are generated from second unicast data.

Transmission data separator 302 outputs multicast packets 3211, 3213,3214, 3216, . . . in this order, to each of APs 2520-1 and 2520-2.Transmission data separator 302 also outputs unicast packets 3212, . . .in this order, to AP 2520-3. Transmission data separator 302 alsooutputs unicast packets 3215, . . . in this order, to AP 2520-4.

(a) Process 1 of Each AP

As illustrated in FIGS. 25 and 32 , AP 2520-1 prepares A1(0), A1(1),A1(2), A1(3), . . . as weights. Likewise, AP 2520-2 prepares A2(0),A2(1), A2(2), A2(3), . . . as weights.

(b) Process 2 of Each AP

Another example of the process of each AP is described below, withreference to FIG. 33 .

(Process of AP 2520-1)

Mapping unit 206 in AP 2520-1 generates mapped baseband signal complexnumbers 3311 “c(0)”, 3312 “c(1)”, 3313 “c(2)”, 3314 “c(3)”, . . . , asillustrated in FIG. 33 .

c(0) is a mapped baseband signal related to packet 3211, c(1) is amapped baseband signal related to packet 3213, c(2) is a mapped basebandsignal related to packet 3214, c(3) is a mapped baseband signal relatedto packet 3216, . . . .

After mapped baseband signal complex number 3311 “c(0)” is generated,weighting unit 2601 in AP 2520-1 calculates c(0)×A1(0) (3331),c(0)×A1(1) (3332), c(0)×A1(2) (3333), and c(0)×A1(3) (3334), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 2520-1 wirelessly outputs c(0)×A1(0) (3331), c(0)×A1(1) (3332),c(0)×A1(2) (3333), and c(0)×A1(3) (3334).

After mapped baseband signal complex number 3312 “c(1)” is generated,weighting unit 2601 in AP 2520-1 calculates c(1)×A1(0) (3335),c(1)×A1(1) (3336), c(1)×A1(2) (3337), and c(1)×A1(3) (3338), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 2520-1 wirelessly outputs c(1)×A1(0) (3335), c(1)×A1(1) (3336),c(1)×A1(2) (3337), and c(1)×A1(3) (3338).

In the case where mapped baseband signal complex numbers 3313 “c(2)”,3314 “c(3)”, . . . are generated, AP 2520-1 operates in the same way asabove.

(Process of AP 2520-2)

Mapping unit 206 in AP 2520-2 generates mapped baseband signal complexnumbers 3311 “c(0)”, 3312 “c(1)”, 3313 “c(2)”, 3314 “c(3)”, . . . , asillustrated in FIG. 33 .

c(0) is a mapped baseband signal related to packet 3211, c(1) is amapped baseband signal related to packet 3213, c(2) is a mapped basebandsignal related to packet 3214, c(3) is a mapped baseband signal relatedto packet 3216, . . . .

After mapped baseband signal complex number 3311 “c(0)” is generated,weighting unit 2601 in AP 2520-2 calculates c(0)×A2(0) (3341),c(0)×A2(1) (3342), c(0)×A2(2) (3343), and c(0)×A2(3) (3344), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 2520-2 wirelessly outputs c(0)×A2(0) (3341), c(0)×A2(1) (3342),c(0)×A2(2) (3343), and c(0)×A2(3) (3344).

After mapped baseband signal complex number 3312 “c(1)” is generated,weighting unit 2601 in AP 2520-2 calculates c(1)×A2(0) (3345),c(1)×A2(1) (3346), c(1)×A2(2) (3347), and c(1)×A2(3) (3348), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 2520-2 wirelessly outputs c(1)×A2(0) (3345), c(1)×A2(1) (3346),c(1)×A2(2) (3347), and c(1)×A2(3) (3348).

In the case where mapped baseband signal complex numbers 3313 “c(2)”,3314 “c(3)”, . . . are generated, AP 2520-2 operates in the same way asabove.

(Process of AP 2520-3)

Mapping unit 206 in AP 2520-3 generates mapped baseband signal complexnumbers “d(0)”, “d(1)”, “d(2)”, . . . d(0) is a mapped baseband signalrelated to packet 3251, d(1) is a mapped baseband signal related topacket 3252, d(2) is a mapped baseband signal related to packet 3253, .. . .

After mapped baseband signal complex number “d(0)” is generated, AP2520-3 wirelessly outputs mapped baseband signal complex number “d(0)”(3351), as illustrated in FIG. 33 .

After mapped baseband signal complex number “d(1)” is generated, AP2520-3 wirelessly outputs mapped baseband signal complex number “d(1)”(3352), as illustrated in FIG. 33 .

Likewise, AP 2520-3 generates mapped baseband signal complex numbers“d(2)”, “d(3)”, “d(4)”, . . . , “d(7)”, . . . , and wirelessly outputsgenerated “d(2)”, “d(3)”, “d(4)”, . . . , “d(7)”, . . . , as illustratedin FIG. 33 .

(Process of AP 2520-4)

Mapping unit 206 in AP 2520-4 generates mapped baseband signal complexnumbers “e(0)”, “e(1)”, “e(2)”, . . . e(0) is a mapped baseband signalrelated to packet 3261, e(1) is a mapped baseband signal related topacket 3262, e(2) is a mapped baseband signal related to packet 3263, .. . .

After mapped baseband signal complex number “e(0)” is generated, AP2520-4 wirelessly outputs mapped baseband signal complex number “e(0)”(3361), as illustrated in FIG. 33 .

After mapped baseband signal complex number “e(1)” is generated, AP2520-4 wirelessly outputs mapped baseband signal complex number “e(1)”(3362), as illustrated in FIG. 33 .

Likewise, AP 2520-4 generates mapped baseband signal complex numbers“e(2)”, “e(3)”, “e(4)”, . . . , “e(7)”, . . . , and wirelessly outputsgenerated “e(2)”, “e(3)”, “e(4)”, . . . , “e(7)”, . . . , as illustratedin FIG. 33 .

Thus, features lie in that each multicast packet is subjected todifferent weighting and transmitted a plurality of times, and that eachmulticast packet is transmitted a plurality of times from a plurality ofAPs.

Transmission using a plurality of APs has the advantageous effect ofwidening the cell area. In addition, transmitting each multicast packeta plurality of times with different weighting has the advantageouseffect of maintaining more uniform reception quality in the cell areabecause the packet is transmitted a plurality of times with differentdirectivity.

Moreover, a flexible system in which APs 2520-3 and 2520-4 can transmitunicast packets is realized.

There is thus the advantage of realizing a flexible system by, forexample, switching the transmission state among the transmission statein FIG. 28 , the transmission state in FIG. 30 , and the transmissionstate in FIG. 32 depending on time (e.g. switching depending on theterminal presence situation).

4.5 Conclusion

According to this embodiment, large-capacity transmission of Gbps levelcan be achieved. Moreover, the number of terminals accommodated in thecase of implementing multicast can be increased. Furthermore, unicastcommunication can be realized simultaneously with multicast. A flexiblesystem can thus be provided.

5. Embodiment 4

Wireless communication system 3400 according to Embodiment 4 as anotherembodiment of the present disclosure is described below.

5.1 Wireless Communication System 3400

Wireless communication system 3400 includes parent station 3410, APs3420-1, 3420-2, 3420-3, and 3420-4, and terminals 3430-1, 3430-2, . . ., 3430-8, as illustrated in FIG. 34 .

Parent station 3410 is connected to a communication device (notillustrated) directly, or indirectly via a communication line. Thecommunication device is, for example, a broadcast device forbroadcasting data or a distribution system or a server for transmittingdata. The communication device transmits a control signal and data. Thecontrol signal includes unicast transmission method-related setting ormulticast transmission method-related setting, and weighting methodsetting. The communication device may include a plurality ofcommunication devices. In this case, a first communication device maytransmit the control signal, and a second communication device maytransmit the data. Parent station 3410 is wiredly (or wirelessly)connected to APs 3420-1, 3420-2, 3420-3, and 3420-4. AP 3420-1 iswiredly (or wirelessly) connected to APs 3420-2, 3420-3, and 3420-4.

Parent station 3410 receives the control signal and the data from thecommunication device. Parent station 3410 transmits the control signalto AP 3420-1. Parent station 3410 transmits the data to each of APs3420-1, 3420-2, 3420-3, and 3420-4. APs 3420-1, 3420-2, 3420-3, and3420-4 wirelessly transmit the data received from parent station 3410.

Terminals 3430-1, 3430-2, . . . , 3430-8 are each a mobile phone, asmartphone, a tablet, or a personal computer (PC) that has a wirelesscommunication function using a frequency bandwidth of 6 GHz or more suchas millimeter wave, e.g. a frequency bandwidth of 60 GHz. Terminal3430-1, for example, wirelessly receives data from AP 3420-1 in the casewhere terminal 3430-1 is located near AP 3420-1. Terminals 3430-2, . . ., 3430-8 each wirelessly receive data from its nearby AP, as withterminal 3430-1.

Terminal 3430-1 also wirelessly transmits data. In the case whereterminal 3430-1 is located near AP 3420-1, AP 3420-1 wirelessly receivesthe data from terminal 3430-1. AP 3420-1 transmits the received data toparent station 3410.

Terminals 3430-2, 3430-3, . . . , 3430-8 each wirelessly transmit data,as with terminal 3430-1. An AP located near each terminal wirelesslyreceives the data from the terminal. The AP transmits the data receivedfrom the terminal, to parent station 3410.

Parent station 3410 receives the data from each terminal, via thecorresponding AP. Parent station 3410 outputs the received data to thecommunication device.

The control signal transmitted from parent station 3410 to AP 3420-1includes unicast transmission-related setting or multicasttransmission-related setting in each AP, and weighting method setting ineach AP. Parent station 3410 does not perform unicasttransmission-related setting and multicast transmission-related settingfor APs 3420-2, 3420-3, and 3420-4. Parent station 3410 does not performweighting method setting for APs 3420-2, 3420-3, and 3420-4.

AP 3420-1 performs unicast transmission-related setting or multicasttransmission-related setting for APs 3420-2, 3420-3, and 3420-4. AP3420-1 also performs weighting method setting for APs 3420-2, 3420-3,and 3420-4.

AP 3420-1 is called “master AP”. APs 3420-2, 3420-3, and 3420-4 arecalled “non-master AP”.

5.2 AP 3420-1 as Master AP

AP 3420-1 as a master AP includes encoder 202, interleaver 204, mappingunit 206, weighting unit 3511, wireless unit 210, antenna 212, antenna215, reception device 217, and indicator 3502, as illustrated in FIG. 35.

AP 3420-1 receives control signal 3501 from parent station 3410. Controlsignal 3501 includes unicast transmission-related setting or multicasttransmission-related setting, and weighting method setting.

AP 3420-1 performs unicast transmission-related setting or multicasttransmission-related setting, based on control signal 3501 received fromparent station 3410. AP 3420-1 also performs weighting method setting,based on control signal 3501. In the case where multicast transmissionsetting is performed, the AP is set to use the same frequency (frequencyband) as other APs.

In the case of performing unicast transmission setting, AP 3420-1operates reception device 217. In the case of performing multicasttransmission setting, AP 3420-1 may stop the operation of receptiondevice 217.

AP 3420-1 performs wireless transmission/reception using the samechannel in the case of unicast transmission and in the case of multicasttransmission. Here, AP 3420-1 may divide one wireless carrier intoseveral time slots, and use each time slot as a communication channel.Alternatively, AP 3420-1 may use each of a plurality of differentfrequencies in the frequency bandwidth of 60 GHz, as a communicationchannel.

(1) Encoder 202

Encoder 202 receives data 201 from parent station 3410. Encoder 202 alsoreceives control signal 213 from a controller included in AP 3420-1.Control signal 213 includes information such as encoding schemedesignation, error correction scheme designation, encoding rate, andblock length. Encoder 202 performs error correction encoding, such asconvolution encoding, LDPC encoding, or turbo encoding, on data 201,using the schemes designated by control signal 213. Encoder 202 outputsencoded data 203.

(2) Interleaver 204

Interleaver 204 receives encoded data 203 from encoder 202. Interleaver204 also receives control signal 213 from the controller included in AP3420-1. Control signal 213 includes interleave method designation.Interleaver 204 performs interleaving, i.e. rearrangement, on encodeddata 203, using the method designated by control signal 213. Interleaver204 outputs interleaved data 205.

(3) Mapping Unit 206

Mapping unit 206 receives interleaved data 205 from interleaver 204.Mapping unit 206 also receives control signal 213 from the controllerincluded in AP 3420-1. Control signal 213 includes modulation schemedesignation. Mapping unit 206 performs modulation, such as quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),or 64 quadrature amplitude modulation (64QAM), on interleaved data 205according to the modulation scheme designation included in controlsignal 213, to generate modulated signal 207. Mapping unit 206 outputsmodulated signal 207. Other modulation schemes may be used.

Mapping unit 206 may perform mapping including a weighting process.

(4) Weighting Unit 3511

Weighting unit 3511 receives modulated signal 207 from mapping unit 206.Weighting unit 3511 also receives control signal 3503_0. Control signal3503_0 includes weighting method setting. Weighting unit 3511 performsweighting on modulated signal 207 according to the weighting methodsetting included in control signal 3503_0, to generate weighted signal3512. Weighting unit 3511 outputs weighted signal 3512.

(5) Wireless Unit 210 and Antenna 212

Wireless unit 210 receives weighted signal 3512 from weighting unit3511. Wireless unit 210 also receives control signal 213 from thecontroller included in AP 3420-1. Control signal 213 includesdesignation of frequency conversion, amplification, etc. Wireless unit210 performs processes such as frequency conversion and amplification onweighted signal 3512, to generate transmission signal 211. Wireless unit210 outputs generated transmission signal 211 to antenna 212, using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz.

Antenna 212 outputs transmission signal 211 as a radio wave.

(6) Antenna 215 and Reception Device 217

Antenna 215 receives signal 216 output from each terminal as a radiowave.

Reception device 217 receives signal 216 from antenna 215 using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz, and performs processes such asamplification and frequency conversion on signal 216, to generate data218. Reception device 217 outputs data 218 to parent station 3410.

Although antennas 212 and 215 are described separately for convenience'ssake, they may be the same entity.

(7) Indicator 3502

Indicator 3502 is connected to parent station 3410.

Indicator 3502 receives control signal 3501 from parent station 3410.Control signal 3501 includes unicast transmission-related setting ormulticast transmission-related setting, and weighting method setting.

Separate control signal 3501 may be set for each AP, or same controlsignal 3501 may be set for all APs.

Indicator 3502 performs multicast transmission setting or unicasttransmission setting for all APs including AP 3420-1, using controlsignals 35030, 35031, . . . , 3503_N.

Here, indicator 3502 may perform multicast transmission setting for allAPs, or perform unicast transmission setting for all APs. Indicator 3502may perform multicast transmission setting for part of the APs, andunicast transmission setting for the other APs. Thus, multicasttransmission setting and unicast transmission setting may be mixed forthe APs.

For a plurality of APs set for multicast transmission, the modulatedsignal before weighting is the same signal. In other words, the samedata is transmitted.

Indicator 3502 also indicates a weighting method to each AP, usingcontrol signals 3503_0, 3503_1, . . . , 3503_N.

For a plurality of APs set for unicast transmission, the modulatedsignal before weighting may be the same signal or a different signal. Inother words, the same data may be transmitted, or different data may betransmitted.

Thus, indicator 3502 generates control signals 3503_0, 3503_1, . . . ,3503_N for the respective APs, from received control signal 3501. Eachcontrol signal includes multicast transmission-related setting orunicast transmission-related setting, and weighting method setting.Indicator 3502 outputs control signals 35030, 3503_1, . . . , 3503_N toitself and APs 3420-2, 3420-3, and 3420-4.

In the case of designating unicast transmission for AP 3420-1, indicator3502 operates reception device 217. In the case of designating multicasttransmission for AP 3420-1, indicator 3502 may stop the operation ofreception device 217.

5.3 Non-Master AP 3600

APs 3420-2, 3420-3, and 3420-4 are each a non-master AP. APs 3420-2,3420-3, and 3420-4 are described below, as AP 3600 collectively.

Non-master AP 3600 includes encoder 202, interleaver 204, mapping unit206, weighting unit 3611, wireless unit 210, antenna 212, antenna 215,and reception device 217, as illustrated in FIG. 36 .

AP 3600 receives control signal 3601_0 from master AP 3420-1. Controlsignal 3601_0 includes unicast transmission-related setting or multicasttransmission-related setting, and weighting method setting. AP 3600 alsoreceives data 3602 from master AP 3420-1. In the case of performing APcooperation, AP 3600 may receive data 3603 from another non-master AP.In the case of operating singly in unicast transmission, AP 3600 mayreceive data 201 from parent station 3410.

AP 3600 performs unicast transmission-related setting or multicasttransmission-related setting, based on control signal 3601_0. AP 3600also performs weighting method setting, based on control signal 3601_0.In the case where multicast transmission is set, the AP is set to usethe same frequency (frequency band) as other APs.

In the case where unicast transmission is set, AP 3600 operatesreception device 217. In the case where multicast transmission is set,AP 3600 may stop the operation of reception device 217.

AP 3600 performs wireless transmission/reception using the same channel(or the same frequency (frequency band)) in the case of unicasttransmission and in the case of multicast transmission. Here, AP 3600may divide one wireless carrier into several time slots, and use eachtime slot as a communication channel. Alternatively, AP 3600 may useeach of a plurality of different frequencies in the frequency bandwidthof 60 GHz, as a communication channel.

(1) Encoder 202

Encoder 202 receives data 3602, 3603, or 201. Encoder 202 also receivescontrol signal 213 from a controller included in AP 3600. Control signal213 includes information such as encoding scheme designation, errorcorrection scheme designation, encoding rate, and block length. Encoder202 performs error correction encoding, such as convolution encoding,LDPC encoding, or turbo encoding, on data 3602, 3603, or 201, using theschemes designated by control signal 213. Encoder 202 outputs encodeddata 203.

(2) Interleaver 204

Interleaver 204 receives encoded data 203 from encoder 202. Interleaver204 also receives control signal 213 from the controller included in AP3600. Control signal 213 includes interleave method designation.Interleaver 204 performs interleaving, i.e. rearrangement, on encodeddata 203, using the method designated by control signal 213. Interleaver204 outputs interleaved data 205.

(3) Mapping Unit 206

Mapping unit 206 receives interleaved data 205 from interleaver 204.Mapping unit 206 also receives control signal 213 from the controllerincluded in AP 3600. Control signal 213 includes modulation schemedesignation. Mapping unit 206 performs modulation, such as quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),or 64 quadrature amplitude modulation (64QAM), on interleaved data 205according to the modulation scheme designation included in controlsignal 213, to generate modulated signal 207. Mapping unit 206 outputsmodulated signal 207. Other modulation schemes may be used.

Mapping unit 206 may perform mapping including a weighting process.

(4) Weighting Unit 3611

Weighting unit 3611 receives modulated signal 207 from mapping unit 206.Weighting unit 3611 also receives control signal 3601_0. Control signal3601_0 includes weighting method setting. Weighting unit 3611 performsweighting on modulated signal 207 according to the weighting methodsetting included in control signal 3601_0, to generate weighted signal3612. Weighting unit 3611 outputs weighted signal 3612.

(5) Wireless Unit 210 and Antenna 212

Wireless unit 210 receives weighted signal 3612 from weighting unit3611. Wireless unit 210 also receives control signal 213 from thecontroller included in AP 3600. Control signal 213 includes designationof frequency conversion, amplification, etc. Wireless unit 210 performsprocesses such as frequency conversion and amplification on weightedsignal 3612, to generate transmission signal 211. Wireless unit 210outputs generated transmission signal 211 to antenna 212, using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz.

Antenna 212 outputs transmission signal 211 as a radio wave.

(6) Antenna 215 and Reception Device 217

Antenna 215 receives signal 216 output from each terminal as a radiowave.

Reception device 217 receives signal 216 from antenna 215 using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz, and performs processes such asamplification and frequency conversion on signal 216, to generate data218. Reception device 217 outputs data 218 to parent station 3410.

Although antennas 212 and 215 are described separately for convenience'ssake, they may be the same entity.

5.4 Parent Station 3410

Parent station 3410 includes transmission data separator 302, receptiondata separator 305, and indicator 308, as illustrated in FIG. 37 .

(1) Indicator 308

Indicator 308 is connected to the communication device and APs 3420-1,3420-2, 3420-3, and 3420-4.

Indicator 308 receives control signal 307. Control signal 307 includesunicast transmission-related setting or multicast transmission-relatedsetting, and weighting method setting. For example, the communicationdevice includes a PC, and the user of the PC inputs the control signalthrough the PC.

Separate control signal 307 may be set for each AP, or same controlsignal 307 may be set for all APs.

Multicast transmission may be set for all APs, or unicast transmissionmay be set for all APs. Multicast transmission may be set for part ofthe APs, and unicast transmission for the other APs. Thus, multicasttransmission-related setting and unicast-related setting may be mixedfor the APs.

For a plurality of APs set for multicast, the modulated signal beforeweighting is the same signal. In other words, the same data istransmitted.

Indicator 308 also indicates a weighting method to each AP.

For a plurality of APs set for unicast, the modulated signal beforeweighting may be the same signal or a different signal. In other words,the same data may be transmitted, or different data may be transmitted.

Indicator 308 outputs the received control signal to transmission dataseparator 302, reception data separator 305, and APs 3420-1, 3420-2,3420-3, and 3420-4.

(2) Transmission Data Separator 302

Transmission data separator 302 is connected to the communicationdevice, indicator 308, and APs 3420-1, 3420-2, 3420-3, and 3420-4.

Transmission data separator 302 receives a control signal from indicator308. Transmission data separator 302 outputs the received control signalto APs 3420-1, 3420-2, 3420-3, and 3420-4.

Transmission data separator 302 also receives data from thecommunication device. Transmission data separator 302 separates thereceived data into data for AP 3420-1, data for AP 3420-2, data for AP3420-3, and data for AP 3420-4. Transmission data separator 302 outputsthe separated data to each of APs 3420-1, 3420-2, 3420-3, and 3420-4.

(3) Reception Data Separator 305

Reception data separator 305 is connected to the communication device,indicator 308, and APs 3420-1, 3420-2, 3420-3, and 3420-4.

Reception data separator 305 receives respective data from APs 3420-1,3420-2, 3420-3, and 3420-4. Reception data separator 305 outputs thereceived data to the communication device.

5.5 Example of Transmitted Data

An example of data transmitted by parent station 3410 and APs 3420-1,3420-2, 3420-3, and 3420-4 is described below.

(1) In the Case of Setting all APs for Multicast Transmission toTransmit Data

An example of transmitted data in the case of setting all APs 3420-1,3420-2, 3420-3, and 3420-4 for multicast transmission to transmit datais described below, with reference to FIGS. 38 and 39 .

Parent station 3410 receives packets 3811, 3812, 3813, 3814, . . . inthis order, as illustrated in FIG. 38 . Packets 3811, 3812, 3813, 3814,. . . are all multicast packets. Packets 3811, 3812, 3813, 3814, . . .are generated from one set of multicast data. Parent station 3410transmits packets 3811, 3812, 3813, 3814, . . . in this order, to AP3420-1.

AP 3420-1 receives packets 3811, 3812, 3813, 3814, . . . in this order.AP 3420-1 then transmits packets 3811, 3812, 3813, 3814, . . . in thisorder, to APs 3420-2, 3420-3, and 3420-4.

(a) Process 1 of Each AP

As illustrated in FIGS. 34 and 38 , AP 3420-1 prepares A1(0), A1(1),A1(2), A1(3), . . . as weights. Likewise, AP 3420-2 prepares A2(0),A2(1), A2(2), A2(3), . . . as weights. AP 3420-3 prepares A3(0), A3(1),A3(2), A3(3), . . . as weights. AP 3420-4 prepares A4(0), A4(1), A4(2),A4(3), . . . as weights.

(b) Process 2 of Each AP

Another example of the process of each AP is described below, withreference to FIG. 39 .

(Process of AP 3420-1)

Mapping unit 206 in AP 3420-1 generates mapped baseband signal complexnumbers 3911 “c(0)”, 3912 “c(1)”, 3913 “c(2)”, 3914 “c(3)”, . . . , asillustrated in FIG. 39 .

c(0) is a mapped baseband signal related to packet 3811, c(1) is amapped baseband signal related to packet 3812, c(2) is a mapped basebandsignal related to packet 3813, c(3) is a mapped baseband signal relatedto packet 3814, . . . .

After mapped baseband signal complex number 3911 “c(0)” is generated,weighting unit 3511 in AP 3420-1 calculates c(0)×A1(0) (3931),c(0)×A1(1) (3932), c(0)×A1(2) (3933), and c(0)×A1(3) (3934), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 3420-1 wirelessly outputs c(0)×A1(0) (3931), c(0)×A1(1) (3932),c(0)×A1(2) (3933), and c(0)×A1(3) (3934).

After mapped baseband signal complex number 3912 “c(1)” is generated,weighting unit 3511 in AP 3420-1 calculates c(1)×A1(0) (3935),c(1)×A1(1) (3936), c(1)×A1(2) (3937), and c(1)×A1(3) (3938), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 3420-1 wirelessly outputs c(1)×A1(0) (3935), c(1)×A1(1) (3936),c(1)×A1(2) (3937), and c(1)×A1(3) (3938).

In the case where mapped baseband signal complex numbers 3913 “c(2)”,3914 “c(3)”, . . . are generated, AP 3420-1 operates in the same way asabove.

(Process of AP 3420-2)

Mapping unit 206 in AP 3420-2 generates mapped baseband signal complexnumbers 3911 “c(0)”, 3912 “c(1)”, 3913 “c(2)”, 3914 “c(3)”, . . . , asillustrated in FIG. 39 .

c(0) is a mapped baseband signal related to packet 3811, c(1) is amapped baseband signal related to packet 3812, c(2) is a mapped basebandsignal related to packet 3813, c(3) is a mapped baseband signal relatedto packet 3814, . . . .

After mapped baseband signal complex number 3911 “c(0)” is generated,weighting unit 3611 in AP 3420-2 calculates c(0)×A2(0) (3941),c(0)×A2(1) (3942), c(0)×A2(2) (3943), and c(0)×A2(3) (3944), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 3420-2 wirelessly outputs c(0)×A2(0) (3941), c(0)×A2(1) (3942),c(0)×A2(2) (3943), and c(0)×A2(3) (3944).

After mapped baseband signal complex number 3912 “c(1)” is generated,weighting unit 3611 in AP 3420-2 calculates c(1)×A2(0) (3945),c(1)×A2(1) (3946), c(1)×A2(2) (3947), and c(1)×A2(3) (3948), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 3420-2 wirelessly outputs c(1)×A2(0) (3945), c(1)×A2(1) (3946),c(1)×A2(2) (3947), and c(1)×A2(3) (3948).

In the case where mapped baseband signal complex numbers 3913 “c(2)”,3914 “c(3)”, . . . are generated, AP 3420-2 operates in the same way asabove.

(Process of APs 3420-3 and 3420-4)

APs 3420-3 and 3420-4 operate in the same way as above.

Here, weighting unit 3611 in AP 3420-3 performs weighting using complexnumbers A3(0), A3(1), A3(2), and A3(3).

Moreover, weighting unit 3611 in AP 3420-4 performs weighting usingcomplex numbers A4(0), A4(1), A4(2), and A4(3).

Thus, features lie in that each packet is subjected to differentweighting and transmitted a plurality of times, and that each packet istransmitted a plurality of times from a plurality of APs.

Transmission using a plurality of APs has the advantageous effect ofwidening the cell area. In addition, transmitting each packet aplurality of times with different weighting has the advantageous effectof maintaining more uniform reception quality in the cell area becausethe packet is transmitted a plurality of times with differentdirectivity.

For example, weighting coefficients A1(i), A2(i), A3(i), and A4(i) havethe following properties.

-   -   Suppose a modulated signal of packet A is transmitted N times (N        is an integer greater than or equal to 2). Let A1(u) be a        weighting coefficient used to transmit the u-th modulated signal        of packet A, and A1(v) be a weighting coefficient used to        transmit the v-th modulated signal of packet A. u and v are each        an integer greater than or equal to 1 and less than or equal to        N, where u≠v. For all u and v that are each an integer greater        than or equal to 1 and less than or equal to N where u≠v,        A1(u)≠A1(v) holds.    -   Equally suppose a modulated signal of packet A is transmitted N        times (N is an integer greater than or equal to 2). Let Ak(u) be        a weighting coefficient used to transmit the u-th modulated        signal of packet A, and Ak(v) be a weighting coefficient used to        transmit the v-th modulated signal of packet A. u and v are each        an integer greater than or equal to 1 and less than or equal to        N, where u≠v. For all u and v that are each an integer greater        than or equal to 1 and less than or equal to N where u≠v,        Ak(u)≠Ak(v) holds (k is an integer greater than or equal to 1).    -   Weighting coefficient Ak(i) may have a cycle. When the cycle is        denoted by M (M is an integer greater than or equal to 2), the        following holds.

[Math. 9]

Ak(i)=Ak(i mod M)  Expression (9).

i mod M is the remainder after division of i by M.

(2) In the Case of Setting APs 3420-1 and 3420-2 for MulticastTransmission and APs 3420-3 and 3420-4 for Unicast Transmission toTransmit Data

An example of transmitted data in the case of setting APs 3420-1 and3420-2 for multicast transmission and APs 3420-3 and 3420-4 for unicasttransmission to transmit data is described below, with reference toFIGS. 40 and 41 . In this case, APs 3420-3 and 3420-4 transmit the samedata (the modulated signal after mapping is the same).

Parent station 3410 receives packets 4011, 4012, 4013, 4014, . . . inthis order, as illustrated in FIG. 40 . Packets 4011, 4013, 4014, 4016,. . . are multicast packets. Packets 4011, 4013, 4014, 4016, . . . aregenerated from one set of multicast data. Packets 4012, 4015, . . . areunicast packets. Packets 4012, 4015, . . . are generated from one set ofunicast data.

Parent station 3410 outputs multicast packets 4011, 4013, 4014, 4016, .. . in this order, to AP 3420-1. Parent station 3410 also outputsunicast packets 4012, 4015, . . . in this order, to each of APs 3420-3and 3420-4.

AP 3420-1 receives multicast packets 4011, 4013, 4014, 4016, . . . inthis order. AP 3420-1 transmits multicast packets 4011, 4013, 4014,4016, . . . in this order, to AP 3420-2.

(a) Process 1 of Each AP

As illustrated in FIGS. 34 and 40 , AP 3420-1 prepares A1(0), A1(1),A1(2), A1(3), . . . as weights. Likewise, AP 3420-2 prepares A2(0),A2(1), A2(2), A2(3), . . . as weights.

(b) Process 2 of Each AP

Another example of the process of each AP is described below, withreference to FIG. 41 .

(Process of AP 3420-1)

Mapping unit 206 in AP 3420-1 generates mapped baseband signal complexnumbers 4111 “c(0)”, 4112 “c(1)”, 4113 “c(2)”, 4114 “c(3)”, . . . , asillustrated in FIG. 41 .

c(0) is a mapped baseband signal related to packet 4011, c(1) is amapped baseband signal related to packet 4013, c(2) is a mapped basebandsignal related to packet 4014, c(3) is a mapped baseband signal relatedto packet 4016, . . . .

After mapped baseband signal complex number 4111 “c(0)” is generated,weighting unit 3511 in AP 3420-1 calculates c(0)×A1(0) (4131),c(0)×A1(1) (4132), c(0)×A1(2) (4133), and c(0)×A1(3) (4134), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 3420-1 wirelessly outputs c(0)×A1(0) (4131), c(0)×A1(i) (4132),c(0)×A1(2) (4133), and c(0)×A1(3) (4134).

After mapped baseband signal complex number 4112 “c(1)” is generated,weighting unit 3511 in AP 3420-1 calculates c(1)×A1(0) (4135),c(1)×A1(1) (4136), c(1)×A1(2) (4137), and c(1)×A1(3) (4138), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 3420-1 wirelessly outputs c(1)×A1(0) (4135), c(1)×A1(1) (4136),c(1)×A1(2) (4137), and c(1)×A1(3) (4138).

In the case where mapped baseband signal complex numbers 4113 “c(2)”,4114 “c(3)”, . . . are generated, AP 3420-1 operates in the same way asabove.

(Process of AP 3420-2)

Mapping unit 206 in AP 3420-2 generates mapped baseband signal complexnumbers 4111 “c(0)”, 4112 “c(1)”, 4113 “c(2)”, 4114 “c(3)”, . . . , asillustrated in FIG. 41 .

c(0) is a mapped baseband signal related to packet 4011, c(1) is amapped baseband signal related to packet 4013, c(2) is a mapped basebandsignal related to packet 4014, c(3) is a mapped baseband signal relatedto packet 4016, . . . .

After mapped baseband signal complex number 4111 “c(0)” is generated,weighting unit 3611 in AP 3420-2 calculates c(0)×A2(0) (4141),c(0)×A2(1) (4142), c(0)×A2(2) (4143), and c(0)×A2(3) (4144), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 3420-2 wirelessly outputs c(0)×A2(0) (4141), c(0)×A2(1) (4142),c(0)×A2(2) (4143), and c(0)×A2(3) (4144).

After mapped baseband signal complex number 4112 “c(1)” is generated,weighting unit 3611 in AP 3420-2 calculates c(1)×A2(0) (4145),c(1)×A2(1) (4146), c(1)×A2(2) (4147), and c(1)×A2(3) (4148), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 3420-2 wirelessly outputs c(1)×A2(0) (4145), c(1)×A2(1) (4146),c(1)×A2(2) (4147), and c(1)×A2(3) (4148).

In the case where mapped baseband signal complex numbers 4113 “c(2)”,4114 “c(3)”, . . . are generated, AP 3420-2 operates in the same way asabove.

(Process of AP 3420-3)

Mapping unit 206 in AP 3420-3 generates mapped baseband signal complexnumbers “d(0)”, “d(1)”, “d(2)”, “d(3)”, . . . d(0) is a mapped basebandsignal related to packet 4051, d(1) is a mapped baseband signal relatedto packet 4052, d(2) is a mapped baseband signal related to packet 4053,. . . .

After mapped baseband signal complex number “d(0)” is generated, AP3420-3 wirelessly outputs generated d(0) (4151).

After mapped baseband signal complex number “d(1)” is generated, AP3420-3 wirelessly outputs generated d(1) (4152).

Likewise, AP 3420-3 generates mapped baseband signal complex numbers“d(2)”, “d(3)”, . . . , and wirelessly outputs generated “d(2)”, “d(3)”,. . . .

(Process of AP 3420-4)

Mapping unit 206 in AP 3420-4 generates mapped baseband signal complexnumbers “d(0)”, “d(1)”, “d(2)”, “d(3)”, . . . d(0) is a mapped basebandsignal related to packet 4061, d(1) is a mapped baseband signal relatedto packet 4062, d(2) is a mapped baseband signal related to packet 4063,. . . .

After mapped baseband signal complex number “d(0)” is generated, AP3420-4 wirelessly outputs generated d(0) (4161).

After mapped baseband signal complex number “d(1)” is generated, AP3420-4 wirelessly outputs generated d(1) (4162).

Likewise, AP 3420-4 generates mapped baseband signal complex numbers“d(2)”, “d(3)”, . . . , and wirelessly outputs generated “d(2)”, “d(3)”,. . . .

Thus, features lie in that each multicast packet is subjected todifferent weighting and transmitted a plurality of times, and that eachmulticast packet is transmitted a plurality of times from a plurality ofAPs.

Transmission using a plurality of APs has the advantageous effect ofwidening the cell area. In addition, transmitting each multicast packeta plurality of times with different weighting has the advantageouseffect of maintaining more uniform reception quality in the cell areabecause the packet is transmitted a plurality of times with differentdirectivity.

In APs 3420-3 and 3420-4, phase change may be performed or weighting maybe changed with respect to time or frequency. This has the advantageouseffect of improving unicast packet reception quality.

(3) In the Case of Setting APs 3420-1 and 3420-2 for MulticastTransmission and APs 3420-3 and 3420-4 for Unicast Transmission toTransmit Data

An example of transmitted data in the case of setting APs 3420-1 and3420-2 for multicast transmission and APs 3420-3 and 3420-4 for unicasttransmission to transmit data is described below, with reference toFIGS. 42 and 43 . In this case, APs 3420-3 and 3420-4 transmit differentdata.

Parent station 3410 receives packets 4211, 4212, 4213, 4214, 4215, 4216,. . . in this order, as illustrated in FIG. 42 . Packets 4211, 4213,4214, 4216, . . . are multicast packets. Packets 4211, 4213, 4214, 4216,. . . are generated from one set of multicast data. Packets 4212, . . .are first unicast packets. Packets 4212, . . . are generated from firstunicast data. Packets 4215, . . . are second unicast packets. Packets4215, . . . are generated from second unicast data.

Parent station 3410 outputs multicast packets 4211, 4213, 4214, 4216, .. . in this order, to AP 3420-1. Parent station 3410 also outputsunicast packets 4212, . . . in this order, to AP 3420-3. Parent station3410 also outputs unicast packets 4215, . . . in this order, to AP3420-4.

AP 3420-1 receives multicast packets 4211, 4213, 4214, 4216, . . . inthis order. AP 3420-1 then transmits multicast packets 4211, 4213, 4214,4216, . . . in this order, to AP 3420-2.

(a) Process 1 of Each AP

As illustrated in FIGS. 34 and 42 , AP 3420-1 prepares A1(0), A1(1),A1(2), A1(3), . . . as weights. Likewise, AP 3420-2 prepares A2(0),A2(1), A2(2), A2(3), . . . as weights.

(b) Process 2 of Each AP

Another example of the process of each AP is described below, withreference to FIG. 43 .

(Process of AP 3420-1)

Mapping unit 206 in AP 3420-1 generates mapped baseband signal complexnumbers 4311 “c(0)”, 4312 “c(1)”, 4313 “c(2)”, 4314 “c(3)”, . . . , asillustrated in FIG. 43 .

c(0) is a mapped baseband signal related to packet 4211, c(1) is amapped baseband signal related to packet 4213, c(2) is a mapped basebandsignal related to packet 4214, c(3) is a mapped baseband signal relatedto packet 4216, . . . .

After mapped baseband signal complex number 4311 “c(0)” is generated,weighting unit 3511 in AP 3420-1 calculates c(0)×A1(0) (4331),c(0)×A1(1) (4332), c(0)×A1(2) (4333), and c(0)×A1(3) (4334), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 3420-1 wirelessly outputs c(0)×A1(0) (4331), c(0)×A1(1) (4332),c(0)×A1(2) (4333), and c(0)×A1(3) (4334).

After mapped baseband signal complex number 4312 “c(1)” is generated,weighting unit 3511 in AP 3420-1 calculates c(1)×A1(0) (4335),c(1)×A1(1) (4336), c(1)×A1(2) (4337), and c(1)×A1(3) (4338), usingcomplex numbers A1(0), A1(1), A1(2), and A1(3).

AP 3420-1 wirelessly outputs c(1)×A1(0) (4335), c(1)×A1(1) (4336),c(1)×A1(2) (4337), and c(1)×A1(3) (4338).

In the case where mapped baseband signal complex numbers 4313 “c(2)”,4314 “c(3)”, . . . are generated, AP 3420-1 operates in the same way asabove.

(Process of AP 3420-2)

Mapping unit 206 in AP 3420-2 generates mapped baseband signal complexnumbers 4311 “c(0)”, 4312 “c(1)”, 4313 “c(2)”, 4314 “c(3)”, . . . , asillustrated in FIG. 43 .

c(0) is a mapped baseband signal related to packet 4211, c(1) is amapped baseband signal related to packet 4213, c(2) is a mapped basebandsignal related to packet 4214, c(3) is a mapped baseband signal relatedto packet 4216, . . . .

After mapped baseband signal complex number 4311 “c(0)” is generated,weighting unit 3611 in AP 3420-2 calculates c(0)×A2(0) (4341),c(0)×A2(1) (4342), c(0)×A2(2) (4343), and c(0)×A2(3) (4344), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 3420-2 wirelessly outputs c(0)×A2(0) (4341), c(0)×A2(1) (4342),c(0)×A2(2) (4343), and c(0)×A2(3) (4344).

After mapped baseband signal complex number 4312 “c(1)” is generated,weighting unit 3611 in AP 3420-2 calculates c(1)×A2(0) (4345),c(1)×A2(1) (4346), c(1)×A2(2) (4347), and c(1)×A2(3) (4348), usingcomplex numbers A2(0), A2(1), A2(2), and A2(3).

AP 3420-2 wirelessly outputs c(1)×A2(0) (4345), c(1)×A2(1) (4346),c(1)×A2(2) (4347), and c(1)×A2(3) (4348).

In the case where mapped baseband signal complex numbers 4313 “c(2)”,4314 “c(3)”, . . . are generated, AP 3420-2 operates in the same way asabove.

(Process of AP 3420-3)

Mapping unit 206 in AP 3420-3 generates mapped baseband signal complexnumbers “d(0)”, “d(1)”, “d(2)”, “d(3)”, . . . d(0) is a mapped basebandsignal related to packet 4251, d(1) is a mapped baseband signal relatedto packet 4252, d(2) is a mapped baseband signal related to packet 4253,. . . .

After mapped baseband signal complex number “d(0)” is generated, AP3420-3 wirelessly outputs generated d(0) (4351).

After mapped baseband signal complex number “d(1)” is generated, AP3420-3 wirelessly outputs generated d(1) (4352).

Likewise, AP 3420-3 generates mapped baseband signal complex numbers“d(2)”, “d(3)”, . . . , and wirelessly outputs generated “d(2)”, “d(3)”,. . . .

(Process of AP 3420-4)

Mapping unit 206 in AP 3420-4 generates mapped baseband signal complexnumbers “e(0)”, “e(1)”, “e(2)”, “e(3)”, . . . e(0) is a mapped basebandsignal related to packet 4261, e(1) is a mapped baseband signal relatedto packet 4262, e(2) is a mapped baseband signal related to packet 4263,. . . .

After mapped baseband signal complex number “e(0)” is generated, AP3420-4 wirelessly outputs generated e(0) (4361).

After mapped baseband signal complex number “e(1)” is generated, AP3420-4 wirelessly outputs generated e(1) (4362).

Likewise, AP 3420-4 generates mapped baseband signal complex numbers“e(2)”, “e(3)”, . . . , and wirelessly outputs generated “e(2)”, “e(3)”. . . .

Thus, features lie in that each multicast packet is subjected todifferent weighting and transmitted a plurality of times, and that eachmulticast packet is transmitted a plurality of times from a plurality ofAPs.

Transmission using a plurality of APs has the advantageous effect ofwidening the cell area. In addition, transmitting each multicast packeta plurality of times with different weighting has the advantageouseffect of maintaining more uniform reception quality in the cell areabecause the packet is transmitted a plurality of times with differentdirectivity.

Moreover, a flexible system in which APs 3420-3 and 3420-4 transmitunicast packets is realized.

There is thus the advantage of realizing a flexible system by, forexample, switching the transmission state among the transmission statein FIG. 38 , the transmission state in FIG. 40 , and the transmissionstate in FIG. 42 depending on time (e.g. switching depending on theterminal presence situation).

5.6 Conclusion

According to this embodiment, large-capacity transmission of Gbps levelcan be achieved. Moreover, the number of terminals accommodated in thecase of implementing multicast can be increased. Furthermore, unicastcommunication can be realized simultaneously with multicast. A flexiblesystem can thus be provided.

6. Embodiment 5

Wireless communication system 4400 according to Embodiment 5 as anotherembodiment of the present disclosure is described below.

6.1 Wireless Communication System 4400

Wireless communication system 4400 includes parent station 4410-1, APs4420-1, 4420-2, 4420-3, and 4420-4, parent station 4410-2, and APs4420-11, 4420-12, 4420-13, and 4420-14, as illustrated in FIG. 44 .

For example, APs 4420-1, 4420-2, 4420-3, and 4420-4 are installed on theroof of building 4451, and parent station 4410-1 is installed insidebuilding 4451. Moreover, APs 4420-11, 4420-12, 4420-13, and 4420-14 areinstalled on the roof of building 4452, and parent station 4410-2 isinstalled inside building 4452. Their installation is, however, notlimited to such.

Consider a use case where there is no obstacle such as another buildingbetween APs 4420-1, 4420-2, 4420-3, and 4420-4 and APs 4420-11, 4420-12,4420-13, and 4420-14 (although such a use case is not a limitation).

In wireless communication system 4400, APs 4420-1, 4420-2, 4420-3, and4420-4 and APs 4420-11, 4420-12, 4420-13, and 4420-14 perform wirelesscommunication between buildings 4451 and 4452.

Parent station 4410-1 is connected to a communication device(communication device A) (not illustrated) holding data transmitted byAPs, either directly or indirectly via a communication line.Communication device A is, for example, a mobile phone, a smartphone, atablet, or a personal computer. Communication device A may be, forexample, a broadcast device for broadcasting data or a distributionsystem or a server for transmitting data. Communication device Atransmits a control signal for controlling the parent station and theAPs, and “data to be transmitted by AP”. The control signal may includeunicast setting. Communication device A may include a plurality ofcommunication devices. In this case, a first communication device maytransmit the control signal, and a second communication device maytransmit the data. Communication device A may be used inside building4451. Communication device A may be used outside buildings 4451 and4452. Parent station 4410-1 is wiredly (or wirelessly) connected to APs4420-1, 4420-2, 4420-3, and 4420-4, and APs 4420-1, 4420-2, 4420-3, and4420-4 transmit data obtained from communication device A.

The control signal includes information of a setting parameter when eachAP performs unicast transmission, and a parameter of a phase changemethod when each AP performs phase change.

AP 4420-1 is called “master AP”. APs 4420-2, 4420-3, and 4420-4 arecalled “non-master AP”.

Parent station 4410-2 is connected to another communication device(communication device B), either directly or indirectly via acommunication line. Communication device B is, for example, a mobilephone, a smartphone, a tablet, or a personal computer. Communicationdevice A may be installed in a building or the like or installedoutdoors, as mentioned above. Communication device B may be used insidebuilding 4452. Communication device B may be used outside buildings 4451and 4452. Parent station 4410-2 is wiredly (or wirelessly) connected toAPs 4420-11, 4420-12, 4420-13, and 4420-14, and APs 4420-11, 4420-12,4420-13, and 4420-14 transmit data obtained from communication device B.

AP 4420-11 is a master AP, and APs 4420-12, 4420-13, and 4420-14 arenon-master APs.

6.2 AP 4420-1 as Master AP

AP 4420-1 as a master AP includes encoder 202, interleaver 204, mappingunit 206, phase changer 208, wireless unit 210, antenna 212, antenna215, reception device 217, and indicator 4402, as illustrated in FIG. 45.

AP 4420-11 is also a master AP, and so has the same structure as masterAP 4420-1.

AP 4420-1 receives control signal 4401 from parent station 4410-1.Control signal 4401 includes unicast transmission setting for each AP,and phase change parameter setting when performing phase change.

AP 4420-1 performs unicast transmission-related setting, based oncontrol signal 4401 received from parent station 4410-1. AP 4420-1 alsoperforms phase change method parameter setting, based on control signal4401.

In the case of performing unicast transmission, AP 4420-1 operatesreception device 217.

(1) Encoder 202

Encoder 202 receives data 201 from parent station 4410-1. Encoder 202also receives control signal 213 from a controller included in AP4420-1. Control signal 213 includes information such as encoding schemedesignation, error correction scheme designation, encoding rate, andblock length. Encoder 202 performs error correction encoding, such asconvolution encoding, LDPC encoding, or turbo encoding, on data 201,using the schemes designated by control signal 213. Encoder 202 outputsencoded data 203.

(2) Interleaver 204

Interleaver 204 receives encoded data 203 from encoder 202. Interleaver204 also receives control signal 213 from the controller included in AP4420-1. Control signal 213 includes interleave method designation.Interleaver 204 performs interleaving, i.e. rearrangement, on encodeddata 203, using the method designated by control signal 213. Interleaver204 outputs interleaved data 205.

(3) Mapping Unit 206

Mapping unit 206 receives interleaved data 205 from interleaver 204.Mapping unit 206 also receives control signal 213 from the controllerincluded in AP 4420-1. Control signal 213 includes modulation schemedesignation. Mapping unit 206 performs modulation, such as quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),or 64 quadrature amplitude modulation (64QAM), on interleaved data 205according to the modulation scheme designation included in controlsignal 213, to generate modulated signal 207. Mapping unit 206 outputsmodulated signal 207. Other modulation schemes may be used.

Mapping unit 206 may perform mapping including a phase change process.

(4) Phase Changer 208

Phase changer 208 receives modulated signal 207 from mapping unit 206.Phase changer 208 also receives control signal 4403_0. Control signal4403_0 includes phase change method setting. Phase changer 208 performsphase change on modulated signal 207 according to the phase changemethod setting included in control signal 4403_0, to generatephase-changed signal 209. Phase changer 208 outputs phase-changed signal209.

(5) Wireless Unit 210 and Antenna 212

Wireless unit 210 receives phase-changed signal 209 from phase changer208. Wireless unit 210 also receives control signal 213 from thecontroller included in AP 4420-1. Control signal 213 includesdesignation of frequency conversion, amplification, etc. Wireless unit210 performs processes such as frequency conversion and amplification onphase-changed signal 209, to generate transmission signal 211. Wirelessunit 210 outputs generated transmission signal 211 to antenna 212, usinga frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz.

Antenna 212 outputs transmission signal 211 as a radio wave.

(6) Antenna 215 and Reception Device 217

Antenna 215 receives signal 216 output from each terminal as a radiowave.

Reception device 217 receives signal 216 from antenna 215 using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz, and performs processes such asamplification and frequency conversion on signal 216, to generate data218. Reception device 217 outputs data 218 to parent station 4410-1.

Although antennas 212 and 215 are described separately for convenience'ssake, they may be the same entity.

(7) Indicator 4402

Indicator 4402 is connected to parent station 4410-1.

Indicator 1902 receives control signal 4401 from parent station 4410-1.Control signal 4401 includes information of unicast-related setting andphase change method setting.

Indicator 4402 provides unicast transmission-related setting informationto all APs including AP 4420-1, based on control signal 4401.

Indicator 4402 also indicates a phase change method to each AP.

Indicator 4402 generates control signals 44030, 4403_1, . . . , 4403_Nfor the respective APs, from received control signal 4401. Each controlsignal includes unicast transmission-related information and phasechange-related information. Indicator 4402 outputs control signals4403_0, 4403_1, . . . , 4403_N to itself and APs 4420-2, 4420-3, and4420-4.

In the case of performing unicast transmission for AP 4420-1, indicator4402 operates reception device 217.

6.3 Non-Master AP 4600

APs 4420-2, 4420-3, and 4420-4 are each a non-master AP. APs 4420-12,4420-13, and 4420-14 are also each a non-master AP.

Operation of APs 4420-2, 4420-3, and 4420-4 is described below, as AP4600 collectively.

Non-master AP 4600 includes encoder 202, interleaver 204, mapping unit206, phase changer 208, wireless unit 210, antenna 212, antenna 215, andreception device 217, as illustrated in FIG. 46 .

AP 4600 receives control signal 4601_0 from AP 4420-1 which is a masterAP. Control signal 4601_0 includes unicast transmission-relatedinformation and phase change-related information. AP 4600 also receivesdata 4602 (not performing AP cooperation) from AP 4420-1 which is amaster AP. In the case of performing AP cooperation, AP 4600 may receivedata 4603 from another AP. AP 4600 may receive data 201 from parentstation 4410-1, and pass the data to another AP.

AP 4600 performs unicast transmission-related setting, based on controlsignal 4601_0. AP 4600 also performs phase change method setting, basedon control signal 4601_0.

In the case of performing unicast setting, AP 4600 operates receptiondevice 217.

(1) Encoder 202

Encoder 202 receives data 4602, 4603, or 201 from parent station 4410_1.Encoder 202 also receives control signal 213 from a controller includedin AP 4600. Control signal 213 includes information such as encodingscheme designation, error correction scheme designation, encoding rate,and block length. Encoder 202 performs error correction encoding, suchas convolution encoding, LDPC encoding, or turbo encoding, on data 4602,4603, or 201, using the schemes designated by control signal 213.Encoder 202 outputs encoded data 203.

(2) Interleaver 204

Interleaver 204 receives encoded data 203 from encoder 202. Interleaver204 also receives control signal 213 from the controller included in AP4600. Control signal 213 includes interleave method designation.Interleaver 204 performs interleaving, i.e. rearrangement, on encodeddata 203, using the method designated by control signal 213. Interleaver204 outputs interleaved data 205.

(3) Mapping Unit 206

Mapping unit 206 receives interleaved data 205 from interleaver 204.Mapping unit 206 also receives control signal 213 from the controllerincluded in AP 4600. Control signal 213 includes modulation schemedesignation. Mapping unit 206 performs modulation, such as quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),or 64 quadrature amplitude modulation (64QAM), on interleaved data 205according to the modulation scheme designation included in controlsignal 213, to generate modulated signal 207. Mapping unit 206 outputsmodulated signal 207. Other modulation schemes may be used.

Mapping unit 206 may perform mapping including a phase change process.

(4) Phase Changer 208

Phase changer 208 receives modulated signal 207 from mapping unit 206.Phase changer 208 also receives control signal 4601_0. Control signal4601_0 includes phase change method setting. Phase changer 208 performsphase change on modulated signal 207 according to the phase changemethod setting included in control signal 4601_0, to generatephase-changed signal 209. Phase changer 208 outputs phase-changed signal209.

(5) Wireless Unit 210 and Antenna 212

Wireless unit 210 receives phase-changed signal 209 from phase changer208. Wireless unit 210 also receives control signal 213 from thecontroller included in AP 4600. Control signal 213 includes designationof frequency conversion, amplification, etc. Wireless unit 210 performsprocesses such as frequency conversion and amplification onphase-changed signal 209, to generate transmission signal 211. Wirelessunit 210 outputs generated transmission signal 211 to antenna 212, usinga frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz.

Antenna 212 outputs transmission signal 211 as a radio wave.

(6) Antenna 215 and Reception Device 217

Antenna 215 receives signal 216 output from each terminal as a radiowave.

Reception device 217 receives signal 216 from antenna 215 using afrequency bandwidth of 6 GHz or more such as millimeter wave, e.g. afrequency bandwidth of 60 GHz, and performs processes such asamplification and frequency conversion on signal 216, to generate data218. Reception device 217 outputs data 218 to parent station 4410-1 or4410-2.

Although antennas 212 and 215 are described separately for convenience'ssake, they may be the same entity.

6.4 Example of Transmitted Data

An example of data transmitted by parent station 4410-1 and APs 4420-1,4420-2, 4420-3, and 4420-4 is described below.

It is assumed here that all APs are set for unicast to performtransmission.

(1) During Clear Weather

An example of transmitted data in the case of setting all APs 4420-1,4420-2, 4420-3, and 4420-4 for unicast to transmit data during clearweather is described below, with reference to FIG. 47 .

(Transmitting Side)

Parent station 4410-1 receives packets 4701, 4702, 4703, . . . , 4706, .. . (packets from the communication device) in this order, asillustrated in FIG. 47 . Packets 4701, 4702, 4703, . . . , 4706, . . .are all unicast packets. Packets 4701, 4705, . . . are generated fromfirst unicast data. Packets 4702, 4706, . . . are generated from secondunicast data. Packets 4703, . . . are generated from third unicast data.Packets 4704, . . . are generated from fourth unicast data.

Parent station 4410-1 transmits packets 4701, 4702, 4703, . . . , 4706,. . . in this order, to AP 4420-1. AP 4420-1 receives packets 4701,4702, 4703, . . . , 4706, . . . in this order.

AP 4420-1 processes, by itself, packets 4701, 4705, . . . generated fromthe first unicast data in this order. AP 4420-1 also transmits packets4702, 4706, . . . generated from the second unicast data in this order,to AP 4420-2. AP 4420-1 also transmits packets 4703, . . . generatedfrom the third unicast data in this order, to AP 4420-3. AP 4420-1 alsotransmits packets 4704, . . . generated from the fourth unicast data inthis order, to AP 4420-4.

AP 4420-1 receives packets 4701, 4705, . . . for itself in this order.Upon receiving packets 4701, 4705, . . . in this order, AP 4420-1wirelessly outputs packets 4711, 4712, 4713, 4714, . . . in this order,in unicast. Packets 4701, 4705, . . . respectively correspond to packets4711, 4712, 4713, 4714.

Upon receiving packets 4702, 4706, . . . in this order, AP 4420-2wirelessly outputs packets 4721, 4722, 4723, 4724, . . . in this order,in unicast. Packets 4702, 4706, . . . respectively correspond to packets4721, 4722, 4723, 4724.

Upon receiving packets 4703, . . . in this order, AP 4420-3 wirelesslyoutputs packets 4731, 4732, 4733, 4734, . . . in this order, in unicast.Packets 4703, . . . respectively correspond to packets 4731, 4732, 4733,4734.

Upon receiving packets 4704, . . . in this order, AP 4420-4 wirelesslyoutputs packets 4741, 4742, 4743, 4744, . . . in this order, in unicast.Packets 4704, . . . respectively correspond to packets 4741, 4742, 4743,4744.

(Receiving Side)

For example, suppose APs 4420-1, 4420-2, 4420-3, 4420-4, 4420-11,4420-12, 4420-13, and 4420-14 in FIG. 44 include antennas that performbeam forming and the like and have strong directivity. In this case,suppose APs 4420-1 and 4420-11 communicate with each other, APs 4420-2and 4420-12 communicate with each other, APs 4420-3 and 4420-13communicate with each other, and APs 4420-4 and 4420-14 communicate witheach other.

Here, reception device 217 in AP 4420-11 receives packets transmittedfrom AP 4420-1. Reception device 217 in AP 4420-12 receives packetstransmitted from AP 4420-2. Reception device 217 in AP 4420-13 receivespackets transmitted from AP 4420-3. Reception device 217 in AP 4420-14receives packets transmitted from AP 4420-4.

In the case where APs 4420-11, 4420-12, 4420-13, and 4420-14simultaneously receive a modulated signal transmitted from AP 4420-1, amodulated signal transmitted from AP 4420-2, a modulated signaltransmitted from AP 4420-3, and a modulated signal transmitted from AP4420-4, the signal received by AP 4420-11, the signal received by AP4420-12, the signal received by AP 4420-13, and the signal received byAP 4420-14 are subjected to a separation process to separate and obtainthe packets.

As another example, suppose parent station 4410-1 obtains only packetU1-#X (X=1, 2, 3, . . . ). In such a case, for example, AP 4420-1transmits packet U1-#X while the other APs stop operation. This reducesthe number of APs in operation, and so has the advantageous effect ofreducing power consumption in the system. During rainfall, transmissionis performed as illustrated in FIG. 48 (the operation in FIG. 48 will bedescribed in detail later). The advantages of this are as follows.

Particularly in the case of transmitting a modulated signal using afrequency in the millimeter wave band, rainfall causes significantattenuation of the signal (radio wave). To maintain a decrease inreception field intensity of the communication partner in a state wheresuch attenuation occurs, the communication device needs to transmit themodulated signal with high average transmission power. However, aregulation value is often imposed on the average transmission power thatcan be transmitted by each communication equipment. Hence, thecommunication device may be unable to transmit the modulated signal withtransmission power increased to such a level of average transmissionpower that can reduce the influence of rainfall attenuation.

In view of this, by transmitting modulated signals including the samedata from a plurality of communication equipment as illustrated in FIG.48 , the advantageous effect that the communication partner has highreception field intensity while each communication device conforms tothe regulation value on the average transmission power can be achieved.

Moreover, by performing such operation that “AP 4420-1 transmits packetU1-#X while the other APs stop operation” during clear weather asmentioned above, the advantageous effect of reducing power consumptionin the system during clear weather can be achieved.

Thus, with different operations of the parent stations and APs betweenclear weather and rainfall, an advantageous system that can flexiblyensure communication quality and control power consumption can berealized.

(2) During Rainfall

An example of transmitted data in the case of setting all APs 4420-1,4420-2, 4420-3, and 4420-4 for unicast to transmit data during rainfallis described below, with reference to FIG. 48 .

(Transmitting Side)

Parent station 4410-1 receives packets 4801, 4802, 4803, . . . , 4806, .. . in this order, as illustrated in FIG. 48 . Packets 4801, 4802, 4803,. . . , 4806, . . . are all unicast packets. Packets 4801, 4802, 4803, .. . , 4806, . . . are generated from one set of unicast data.

Parent station 4410-1 transmits packets 4801, 4802, 4803, . . . , 4806,. . . in this order, to AP 4420-1.

AP 4420-1 receives packets 4801, 4802, 4803, . . . , 4806, . . . in thisorder, and processes packets 4801, 4802, 4803, . . . , 4806, . . . inthis order. AP 4420-1 transmits packets 4801, 4802, 4803, . . . , 4806,. . . in this order, to each of APs 4420-2, 4420-3, and 4420-4.

AP 4420-1 receives packets 4801, 4802, 4803, . . . , 4806, . . . in thisorder. Upon receiving packets 4801, 4802, 4803, . . . , 4806, . . . inthis order, AP 4420-1 wirelessly outputs packets 4811, 4812, 4813, 4814,. . . in this order, in unicast. Packets 4801, 4802, 4803, . . . , 4806,. . . respectively correspond to packets 4811, 4812, 4813, 4814.

AP 4420-2 receives packets 4801, 4802, 4803, . . . , 4806, . . . in thisorder. Upon receiving packets 4801, 4802, 4803, . . . , 4806, . . . inthis order, AP 4420-2 wirelessly outputs packets 4821, 4822, 4823, 4824,. . . in this order in unicast, under control of AP 4420-1 which is amaster AP. Packets 4801, 4802, 4803, . . . , 4806, . . . respectivelycorrespond to packets 4821, 4822, 4823, 4824.

AP 4420-3 receives packets 4801, 4802, 4803, . . . , 4806, . . . in thisorder. Upon receiving packets 4801, 4802, 4803, . . . , 4806, . . . inthis order, AP 4420-3 wirelessly outputs packets 4831, 4832, 4833, 4834,. . . in this order in unicast, under control of AP 4420-1 which is amaster AP. Packets 4801, 4802, 4803, . . . , 4806, . . . respectivelycorrespond to packets 4831, 4832, 4833, 4834.

AP 4420-4 receives packets 4801, 4802, 4803, . . . , 4806, . . . in thisorder. Upon receiving packets 4801, 4802, 4803, . . . , 4806, . . . inthis order, AP 4420-4 wirelessly outputs packets 4841, 4842, 4843, 4844,. . . in this order in unicast, under control of AP 4420-1 which is amaster AP. Packets 4801, 4802, 4803, . . . , 4806, . . . respectivelycorrespond to packets 4841, 4842, 4843, 4844.

A feature lies in that APs 4420-1, 4420-2, 4420-3, and 4420-4 transmitthe same packets at the same time (the modulated signals after mappingat the same time are the same), as described in the other embodiments.Therefore, AP 4420-1 performs phase change, AP 4420-2 performs phasechange, AP 4420-3 performs phase change, and also AP 4420-4 performsphase change (alternatively, any of APs 4420-1, 4420-2, 4420-3, and4420-4 may perform no phase change).

Although FIG. 48 illustrates an example where four APs are present andtransmit packet U1-#X (X=1, 2, 3, . . . ), this is not a limitation. Forexample, N APs (N is an integer greater than or equal to 2) may bepresent, where M APs (M is an integer less than or equal to N, andgreater than or equal to 2) transmit packet U1-#X (X=1, 2, 3, . . . ).

The following structure can be derived from the above.

N APs (N is an integer greater than or equal to 2) are present. Duringclear weather (when radio wave attenuation due to rainfall is low (asituation where it is raining but radio wave attenuation is low isregarded as “during clear weather”)), L APs (L is an integer greaterthan or equal to 1, and less than or equal to N−1) transmit packet U1-#X(X=1, 2, 3, . . . ).

During rainfall (when radio wave attenuation due to rainfall is high), MAPs (M is an integer less than or equal to N, greater than or equal to2, and greater than L) may transmit packet U1-#X (X=1, 2, 3, . . . ).

By such transmission, a decrease in reception quality of thecommunication partner caused by propagation attenuation during rainfallcan be suppressed, so that an advantageous system that can flexiblyensure communication quality and control power consumption can berealized. During clear weather, any AP not transmitting packet U1-#X maytransmit other packets (or not transmit other packets). Likewise, duringrainfall, any AP not transmitting packet U1-#X may transmit otherpackets (or not transmit other packets).

(Receiving Side)

Reception device 217 in AP 4420-11 simultaneously receives a modulatedsignal corresponding to packet 4811, a modulated signal corresponding topacket 4821, a modulated signal corresponding to packet 4831, and amodulated signal corresponding to packet 4841. Reception device 217 inAP 4420-11 then simultaneously receives a modulated signal correspondingto packet 4812, a modulated signal corresponding to packet 4822, amodulated signal corresponding to packet 4832, and a modulated signalcorresponding to packet 4842. Reception device 217 in AP 4420-11 thensimultaneously receives a modulated signal corresponding to packet 4813,a modulated signal corresponding to packet 4823, a modulated signalcorresponding to packet 4833, and a modulated signal corresponding topacket 4843. Reception device 217 in AP 4420-11 then simultaneouslyreceives a modulated signal corresponding to packet 4814, a modulatedsignal corresponding to packet 4824, a modulated signal corresponding topacket 4834, and a modulated signal corresponding to packet 4844.

By demodulating/decoding the synthesized reception signal, packets 4801,4802, 4803, 4804, 4805, . . . can be obtained.

6.5 Operation of AP 4420-1 as Master AP

The operation of AP 4420-1 which is a master AP is described below, withreference to a flowchart in FIG. 49 .

Indicator 4402 in AP 4420-1 which is a master AP obtains communicationquality of communication with AP 4420-11 which is a communicationpartner (Step S4901). Indicator 4402 then determines whether or not theobtained communication quality is not less than a threshold (StepS4902).

In the case where the obtained communication quality is less than thethreshold (Step S4902: “less than threshold”), for example, indicator4402 causes APs 4420-2, 4420-3, and 4420-4 to perform cooperativeoperation to transmit the same data (Step S4903). Indicator 4402 thenreturns to Step S4901 and repeats the process.

In the case where the obtained communication quality is not less thanthe threshold (Step S4902: “not less than threshold”), for example,indicator 4402 stops the cooperative operation of APs 4420-2, 4420-3,and 4420-4 (stops the transmission of the same data) (Step S4904). Forexample, indicator 4402 causes APs 4420-2, 4420-3, and 4420-4 to resumeindependent operation. The independent operation is operation before thecooperative operation starts (Step S4905). Indicator 4402 then returnsto Step S4901 and repeats the process.

6.6 Transmission of Training Signal by Each AP

For example, AP 4420-1 transmits a training signal both during clearweather, and during rainfall. A communication partner receives thetraining signal, and transmits the reception result to AP 4420-1. AP4420-1 obtains the reception result, thus obtaining communicationquality with the AP on the receiving side. AP 4420-1 determines whetherto perform or stop the above-mentioned cooperative operation, using theobtained communication quality. AP 4420-1 transmits the resultindicating “whether to perform or stop cooperative operation”, to APs4420-2, 4420-3, and 4420-4 (here, AP 4420-1 may transmit “whether toperform or stop cooperative operation” to APs 4420-2, 4420-3, and 4420-4via the parent station, or transmit “whether to perform or stopcooperative operation” directly to APs 4420-2, 4420-3, and 4420-4). Inthe case of determining to “perform cooperative operation”, AP 4420-1transmits information about a phase change value method, a modulationscheme, and encoding method to be used, to APs 4420-2, 4420-3, and4420-4 (here, AP 4420-1 may transmit information about a phase changevalue method, a modulation scheme, and encoding method to be used, toAPs 4420-2, 4420-3, and 4420-4 via the parent station).

In this embodiment, no mode for setting “multicast” may be provided (forexample, in the case of applying this embodiment to a communicationdevice installed in a building and a communication device installed in abuilding, there may be instances where multicast need not be performed).

Although the above describes an example where a master AP and non-masterAPs perform cooperative operation, cooperative operation in the casewhere a parent station has part of the functions of a master AP asillustrated in FIGS. 1, 25 , etc. may be employed in switching the framestructure as illustrated in FIG. 47 and the frame structure asillustrated in FIG. 48 during clear weather and during rainfall. Thestructure of a transmission system for switching cooperative operationbetween during clear weather and during rainfall is not limited tosuch., and the above-mentioned function of “switching cooperativeoperation between during clear weather and during rainfall” per se isimportant.

6.4 Conclusion

According to this embodiment, large-capacity transmission of Gbps can beachieved. In addition, wireless communication can be ensured even in thecase of rainfall. Furthermore, since the master AP stops cooperativeoperation when returning to clear weather from rainfall, so thatunnecessary power consumption caused by performing cooperative operationduring clear weather can be prevented.

Although the above embodiment describes the case where four APs performcooperative operation, this is not a limitation. Two or more APs mayperform cooperative operation.

SUPPLEMENTARY REMARKS

The embodiments and other contents in this description may be combined.

The embodiments and other contents are merely illustrative. For example,even when “modulation scheme, error (loss) correction encoding scheme(error correction encoding, code length, encoding rate, etc.), controlinformation, etc.” are illustrated, other “modulation scheme, error(loss) correction encoding scheme (error correction encoding, codelength, encoding rate, etc.), control information, etc.” may besimilarly used in the same structure.

The embodiments and other contents in this description can be carriedout using modulation schemes other than the modulation schemes mentionedin this description. Examples include amplitude phase shift keying(APSK) (e.g. 16APSK, 64APSK, 128APSK, 256APSK, 1024APSK, 4096APSK,etc.), pulse amplitude modulation (PAM) (e.g. 4PAM, 8PAM, 16PAM, 64PAM,128PAM, 256PAM, 1024PAM, 4096PAM, etc.), phase shift keying (PSK) (e.g.BPSK, QPSK, 8PSK, 16PSK, 64PSK, 128PSK, 256PSK, 1024PSK, 4096PSK, etc.),and quadrature amplitude modulation (QAM) (e.g. 4QAM, 8QAM, 16QAM,64QAM, 128QAM, 256QAM, 1024QAM, 4096QAM, etc.). In each modulationscheme, uniform mapping or non-uniform mapping may be used.

The transmission method in the wireless communication scheme may be atransmission method (SISO (Single-Input Single-Output) transmissionmethod, SIMO (Single-Input Multiple-Output) transmission method) inwhich a transmission device has one antenna and a reception devicereceives a signal with one or more antennas, or a transmission method(MIMO (Multiple-Input Multiple-Output) transmission method, MISO(Multiple-Input Single-Output) transmission method) in which atransmission device transmits a plurality of streams and a receptiondevice receives a modulated signal with one or more antennas. Moreover,space-time block encoding or space-time trellis encoding may be used (inthe case of using a multicarrier scheme such as OFDM, symbols may bearranged in a time axis direction, in a frequency axis direction, or ina frequency-time axis direction).

The term “complex number” in this description is used to refer to“defining in a complex number”, which includes a real number with animaginary component being 0.

The present disclosure is not limited to the above embodiments, and canbe implemented in any form for achieving the object according to thepresent disclosure and its related or subsidiary object. For example,the following are applicable.

(1) The operation procedure of the communication device on thecommunication station side described in each of the above embodimentsmay be described in a program, and the program may be stored in readonly memory (ROM) beforehand. A central processing unit (CPU) may thenread the program stored in the ROM and execute it. Alternatively, theprogram describing the operation procedure of the communication deviceon the communication station side may be stored in a computer-readablestorage medium and loaded into random access memory (RAM) in a computer.A CPU of the computer may then read the program stored in the RAM andexecute it.

(2) The structural elements in each of the above embodiments may betypically realized by large scale integration (LSI) which is anintegrated circuit. The structural elements may each be individuallyimplemented as one chip, or may be partly or wholly implemented on onechip.

Although LSI is mentioned here, the integrated circuit may be called(integrated circuit) IC, system LSI, super LSI, or ultra LSI, dependingon the degree of integration.

The integrated circuit technology is not limited to LSI, and may berealized by a dedicated circuit or a general-purpose processor. A fieldprogrammable gate array (FPGA) which can be programmed or areconfigurable processor which is capable of reconfiguring connectionsand settings of circuit cells in LSI after LSI manufacturing may beused.

Furthermore, when an integrated circuit technology that replaces LSIemerges from development of semiconductor technologies or otherderivative technologies, such a technology may be used to integrate thefunctional blocks. For instance, biotechnology may be adapted in thisway.

In this description, for example, communication/broadcast equipment suchas a broadcast station, a base station, an access point, a terminal, ora mobile phone includes a transmission device, and communicationequipment such as a television, a radio, a terminal, a personalcomputer, a mobile phone, an access point, or a base station includes areception device. A transmission device and a reception device accordingto the present disclosure may be equipment that has a communicationfunction and can be connected, via some kind of interface, to a devicefor executing an application such as a television, a radio, a personalcomputer, or a mobile phone.

In each embodiment, symbols other than data symbols, such as pilotsymbols (pre-amble, unique word, post-amble, reference symbol, etc.) andcontrol information symbols, may be arranged in a frame in any way.Although the terms such as pilot symbols and control information symbolsare used here, any terms may be used, and the functions per se areimportant.

For example, a pilot symbol is any known symbol modulated in atransmitter/receiver using PSK modulation (alternatively, the receivermay be able to know the symbol transmitted by the transmitter, throughsynchronization). The receiver performs frequency synchronization, timesynchronization, channel estimation (channel state information (CSI)estimation) (of each modulated signal), signal detection, etc., usingthis symbol.

A control information symbol is a symbol for transmitting information(e.g. modulation scheme, error (loss) correction encoding scheme,encoding rate in error (loss) correction encoding scheme, upper layersetting information, etc. used in communication) that needs to betransmitted to the communication partner to realize communication ofinformation (e.g. application) other than data.

The transmission device and the reception device need to be notified ofa transmission method (MIMO, SISO, space-time block encoding, interleavescheme), a modulation scheme, an error correction encoding scheme, and apacket-level error (loss) correction scheme, although the description ofthis part is omitted in some embodiments. A symbol for transmittingthese information is present in a frame transmitted by the transmissiondevice, with the reception device obtaining the symbol and changing itsoperation.

The present disclosure is not limited to the above embodiments, andvarious modifications are possible. For example, although each of theabove embodiments is carried out as a communication device, this is nota limitation, and its communication method may be realized as software.

INDUSTRIAL APPLICABILITY

A transmission method according to the present disclosure enableswireless transmission in a plurality of transmission devices using amillimeter wave frequency bandwidth, and so is useful as a wirelesscommunication technique.

REFERENCE MARKS IN THE DRAWINGS

-   -   110 parent station    -   121 to 124 AP    -   131 to 138 terminal    -   202 encoder    -   204 interleaver    -   206 mapping unit    -   208 phase changer    -   210 wireless unit    -   212 antenna    -   215 antenna    -   217 reception device    -   302 transmission data separator    -   305 reception data separator    -   308 indicator    -   100, 1400, 1500, 1600 wireless communication system    -   1800, 2500, 3400, 4400 wireless communication system

1-5. (canceled)
 6. A terminal comprising: at least one antenna; and areceiver coupled to the at least one antenna to receive first data andsecond data in a first resource and a second resource, respectively, thefirst data being the same as the second data, wherein in a first mode,the first resource and the second resource are a first frequency channeland a second frequency channel, respectively, in a second mode, thefirst resource and the second resource are a first time slot and asecond time slot, respectively, and the first data and the second datado not include control information.
 7. The terminal according to claim6, wherein the first resource and the second resource are used by afirst transmission point and a second transmission point, respectively.8. The terminal according to claim 7, wherein in a third mode, thereceiver receives third data other than the control information from oneof the first transmission point and the second transmission point.